Creating a dynamic and responsive person interface is important for immoderate palmy iOS app. Mastering Car Structure is indispensable for this, and knowing however to adhd constraints programmatically utilizing Swift provides you unparalleled power complete your UI parts. This permits you to accommodate to antithetic surface sizes, orientations, and contented variations with easiness, starring to a seamless person education. This blanket usher volition locomotion you done the procedure of including constraints programmatically successful Swift, equipping you with the expertise to physique genuinely adaptive and participating interfaces.
Knowing Car Structure
Car Format is a almighty scheme that defines the relationships betwixt UI components, dictating their assumption and dimension. Alternatively of hardcoding fastened frames, Car Structure makes use of constraints to depict however views ought to associate to all another. This attack ensures your UI adapts gracefully crossed assorted gadgets and surface sizes. Deliberation of constraints arsenic guidelines that govern the structure, permitting your app to expression large connected all the pieces from an iPhone SE to an iPad Professional.
Earlier diving into programmatic constraints, it’s generous to realize however Car Structure plant visually successful Interface Builder. This instauration volition aid you interpret these ocular relationships into codification. By exploring the antithetic constraint sorts and their properties, you’ll addition a deeper knowing of however to manipulate them programmatically.
A cardinal conception successful Car Structure is the thought of anchors. Anchors correspond circumstantial factors connected a position, specified arsenic its apical, bottommost, starring, and trailing edges, arsenic fine arsenic its halfway. These anchors are utilized to make constraints, defining the relationships betwixt views.
Mounting Ahead for Programmatic Constraints
Earlier including constraints programmatically, you demand to brand a important accommodation: disable translatesAutoresizingMaskIntoConstraints. Once this place is actual (the default), the scheme robotically generates constraints primarily based connected a position’s framework. This volition struggle with the constraints you adhd programmatically. So, ever fit this place to mendacious earlier including your ain constraints.
Presentโs however you bash it:
myView.translatesAutoresizingMaskIntoConstraints = mendacious
This formation of codification tells the scheme that you’ll beryllium managing the format of myView done specific constraints, giving you afloat power.
Retrieve, failing to disable this place is a communal origin of vexation once running with programmatic constraints. Ever treble-cheque this measure to debar sudden format points.
Including Constraints Programmatically
Present, fto’s adhd any constraints. We’ll commencement with a elemental illustration: centering a position inside its genitor. We’ll usage the NSLayoutConstraint people and the isActive place for a concise and readable attack.
fto centerXConstraint = myView.centerXAnchor.constraint(equalTo: position.centerXAnchor) fto centerYConstraint = myView.centerYAnchor.constraint(equalTo: position.centerYAnchor) centerXConstraint.isActive = actual centerYConstraint.isActive = actual
This codification creates 2 constraints: 1 centering myView horizontally and different vertically inside its genitor position. Mounting isActive to actual prompts the constraints, making use of them to the structure.
This method offers a cleanable and businesslike manner to adhd constraints programmatically, guaranteeing your UI parts are positioned appropriately.
Running with Antithetic Constraint Varieties
Past centering, you tin make assorted sorts of constraints to power the measurement and assumption of your views. For case, you tin fit width and tallness constraints:
fto widthConstraint = myView.widthAnchor.constraint(equalToConstant: 200) fto heightConstraint = myView.heightAnchor.constraint(equalToConstant: one hundred) widthConstraint.isActive = actual heightConstraint.isActive = actual
You tin besides make constraints comparative to another views. This permits you to specify relationships similar starring, trailing, apical, and bottommost spacing:
fto leadingConstraint = myView.leadingAnchor.constraint(equalTo: anotherView.trailingAnchor, changeless: 20) leadingConstraint.isActive = actual
This codification positions myView 20 factors to the correct of anotherView.
- Make the most of Ocular Format Communication for analyzable layouts.
- Research the
NSLayoutAnchorpeople for a much intuitive attack.
Precocious Methods and Champion Practices
For much analyzable situations, see utilizing Ocular Format Communication (VFL) oregon the NSLayoutAnchor API. VFL provides a drawstring-primarily based syntax for defining constraints, piece NSLayoutAnchor supplies a kind-harmless and much readable alternate. Selecting the correct attack relies upon connected your circumstantial wants and preferences.
Debugging constraints tin beryllium difficult. Usage Xcode’s position debugger and constraint logging to place and resoluteness format points efficaciously.
- Program your structure cautiously.
- Disable
translatesAutoresizingMaskIntoConstraints. - Adhd your constraints.
- Trial totally connected antithetic gadgets and orientations.
Infographic Placeholder: Visualizing Constraint Relationships
By mastering programmatic constraints, you addition exact power complete your UI format, enabling you to physique genuinely responsive and adaptive interfaces that delight customers crossed each gadgets. Itโs a cornerstone of nonrecreational iOS improvement and worthy the attempt to larn. This accomplishment permits you to make dynamic and versatile layouts that accommodate seamlessly to antithetic surface sizes, orientations, and contented variations.
For additional exploration, mention to Pomeโs authoritative documentation connected Car Structure present and research Ray Wenderlichโs tutorials present.
Cheque retired this inner nexus for much particulars.
Constraints besides activity with stack views, making analyzable layouts simpler to negociate. Research Stack Views for much streamlined format plan.
FAQ
Q: What are communal errors once including constraints programmatically?
A: Forgetting to disable translatesAutoresizingMaskIntoConstraints is a predominant mistake. Besides, guarantee you person added adequate constraints to full specify the assumption and dimension of your views, however not truthful galore that they struggle.
Return your Swift improvement expertise to the adjacent flat. Commencement experimenting with programmatic constraints present and unlock the afloat possible of Car Format. Retrieve, pattern is cardinal. The much you activity with programmatic constraints, the much comfy and proficient you’ll go. This almighty implement volition empower you to make extremely adaptable and participating person interfaces that base retired. Dive deeper into circumstantial format challenges and detect however programmatic constraints tin aid you flooded them.
Question & Answer :
I’m attempting to fig this retired since past week with out going immoderate measure additional. Fine, truthful I demand to use any constraints programmatically successful Swift to a UIView utilizing this codification:
var new_view:UIView! = UIView(framework: CGRectMake(zero, zero, a hundred, one hundred)); new_view.backgroundColor = UIColor.redColor(); position.addSubview(new_view); var constX:NSLayoutConstraint = NSLayoutConstraint(point: new_view, property: NSLayoutAttribute.CenterX, relatedBy: NSLayoutRelation.Close, toItem: same.position, property: NSLayoutAttribute.CenterX, multiplier: 1, changeless: zero); same.position.addConstraint(constX); var constY:NSLayoutConstraint = NSLayoutConstraint(point: new_view, property: NSLayoutAttribute.CenterY, relatedBy: NSLayoutRelation.Close, toItem: same.position, property: NSLayoutAttribute.CenterY, multiplier: 1, changeless: zero); same.position.addConstraint(constY); var constW:NSLayoutConstraint = NSLayoutConstraint(point: new_view, property: NSLayoutAttribute.Width, relatedBy: NSLayoutRelation.Close, toItem: new_view, property: NSLayoutAttribute.Width, multiplier: 1, changeless: zero); same.position.addConstraint(constW); var constH:NSLayoutConstraint = NSLayoutConstraint(point: new_view, property: NSLayoutAttribute.Tallness, relatedBy: NSLayoutRelation.Close, toItem: new_view, property: NSLayoutAttribute.Tallness, multiplier: 1, changeless: zero); same.position.addConstraint(constH);
However Xcode returns this bizarre output:
2014-10-03 09:forty eight:12.657 Trial[35088:2454916] Incapable to concurrently fulfill constraints. Most likely astatine slightest 1 of the constraints successful the pursuing database is 1 you don't privation. Attempt this: (1) expression astatine all constraint and attempt to fig retired which you don't anticipate; (2) discovery the codification that added the undesirable constraint oregon constraints and hole it. (Line: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't realize, mention to the documentation for the UIView place translatesAutoresizingMaskIntoConstraints) ( "<NSLayoutConstraint:0x7fa4ea446830 UIView:0x7fa4ea429290.centerX == UIView:0x7fa4ea4470f0.centerX>", "<NSAutoresizingMaskLayoutConstraint:0x7fa4ea4516c0 h=--& v=--& UIView:0x7fa4ea429290.midX == + 50>", "<NSLayoutConstraint:0x7fa4ea452830 'UIView-Encapsulated-Format-Width' H:[UIView:0x7fa4ea4470f0(375)]>", "<NSAutoresizingMaskLayoutConstraint:0x7fa4ea446db0 h=-&- v=-&- 'UIView-Encapsulated-Structure-Near' H:|-(zero)-[UIView:0x7fa4ea4470f0] (Names: '|':UIWindow:0x7fa4ea444b20 )>" ) Volition effort to retrieve by breaking constraint <NSLayoutConstraint:0x7fa4ea446830 UIView:0x7fa4ea429290.centerX == UIView:0x7fa4ea4470f0.centerX> Brand a symbolic breakpoint astatine UIViewAlertForUnsatisfiableConstraints to drawback this successful the debugger. The strategies successful the UIConstraintBasedLayoutDebugging class connected UIView listed successful <UIKit/UIView.h> whitethorn besides beryllium adjuvant. 2014-10-03 09:forty eight:12.658 Trial[35088:2454916] Incapable to concurrently fulfill constraints. Most likely astatine slightest 1 of the constraints successful the pursuing database is 1 you don't privation. Attempt this: (1) expression astatine all constraint and attempt to fig retired which you don't anticipate; (2) discovery the codification that added the undesirable constraint oregon constraints and hole it. (Line: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't realize, mention to the documentation for the UIView place translatesAutoresizingMaskIntoConstraints) ( "<NSLayoutConstraint:0x7fa4ea44d160 UIView:0x7fa4ea429290.centerY == UIView:0x7fa4ea4470f0.centerY>", "<NSAutoresizingMaskLayoutConstraint:0x7fa4ea451b30 h=--& v=--& UIView:0x7fa4ea429290.midY == + 50>", "<NSLayoutConstraint:0x7fa4ea44cf00 'UIView-Encapsulated-Structure-Tallness' V:[UIView:0x7fa4ea4470f0(667)]>", "<NSAutoresizingMaskLayoutConstraint:0x7fa4ea452700 h=-&- v=-&- 'UIView-Encapsulated-Structure-Apical' V:|-(zero)-[UIView:0x7fa4ea4470f0] (Names: '|':UIWindow:0x7fa4ea444b20 )>" ) Volition effort to retrieve by breaking constraint <NSLayoutConstraint:0x7fa4ea44d160 UIView:0x7fa4ea429290.centerY == UIView:0x7fa4ea4470f0.centerY> Brand a symbolic breakpoint astatine UIViewAlertForUnsatisfiableConstraints to drawback this successful the debugger. The strategies successful the UIConstraintBasedLayoutDebugging class connected UIView listed successful <UIKit/UIView.h> whitethorn besides beryllium adjuvant.
Tin you aid maine? Acknowledgment a batch
Bash you program to person a squared UIView of width: a hundred and Tallness: one hundred centered wrong the UIView of an UIViewController? If truthful, you whitethorn attempt 1 of the 6 pursuing Car Format kinds (Swift 5 / iOS 12.2):
1. Utilizing NSLayoutConstraint initializer
override func viewDidLoad() { fto newView = UIView() newView.backgroundColor = UIColor.reddish position.addSubview(newView) newView.translatesAutoresizingMaskIntoConstraints = mendacious fto horizontalConstraint = NSLayoutConstraint(point: newView, property: NSLayoutConstraint.Property.centerX, relatedBy: NSLayoutConstraint.Narration.close, toItem: position, property: NSLayoutConstraint.Property.centerX, multiplier: 1, changeless: zero) fto verticalConstraint = NSLayoutConstraint(point: newView, property: NSLayoutConstraint.Property.centerY, relatedBy: NSLayoutConstraint.Narration.close, toItem: position, property: NSLayoutConstraint.Property.centerY, multiplier: 1, changeless: zero) fto widthConstraint = NSLayoutConstraint(point: newView, property: NSLayoutConstraint.Property.width, relatedBy: NSLayoutConstraint.Narration.close, toItem: nil, property: NSLayoutConstraint.Property.notAnAttribute, multiplier: 1, changeless: a hundred) fto heightConstraint = NSLayoutConstraint(point: newView, property: NSLayoutConstraint.Property.tallness, relatedBy: NSLayoutConstraint.Narration.close, toItem: nil, property: NSLayoutConstraint.Property.notAnAttribute, multiplier: 1, changeless: a hundred) position.addConstraints([horizontalConstraint, verticalConstraint, widthConstraint, heightConstraint]) }
override func viewDidLoad() { fto newView = UIView() newView.backgroundColor = UIColor.reddish position.addSubview(newView) newView.translatesAutoresizingMaskIntoConstraints = mendacious fto horizontalConstraint = NSLayoutConstraint(point: newView, property: NSLayoutConstraint.Property.centerX, relatedBy: NSLayoutConstraint.Narration.close, toItem: position, property: NSLayoutConstraint.Property.centerX, multiplier: 1, changeless: zero) fto verticalConstraint = NSLayoutConstraint(point: newView, property: NSLayoutConstraint.Property.centerY, relatedBy: NSLayoutConstraint.Narration.close, toItem: position, property: NSLayoutConstraint.Property.centerY, multiplier: 1, changeless: zero) fto widthConstraint = NSLayoutConstraint(point: newView, property: NSLayoutConstraint.Property.width, relatedBy: NSLayoutConstraint.Narration.close, toItem: nil, property: NSLayoutConstraint.Property.notAnAttribute, multiplier: 1, changeless: one hundred) fto heightConstraint = NSLayoutConstraint(point: newView, property: NSLayoutConstraint.Property.tallness, relatedBy: NSLayoutConstraint.Narration.close, toItem: nil, property: NSLayoutConstraint.Property.notAnAttribute, multiplier: 1, changeless: a hundred) NSLayoutConstraint.activate([horizontalConstraint, verticalConstraint, widthConstraint, heightConstraint]) }
override func viewDidLoad() { fto newView = UIView() newView.backgroundColor = UIColor.reddish position.addSubview(newView) newView.translatesAutoresizingMaskIntoConstraints = mendacious NSLayoutConstraint(point: newView, property: NSLayoutConstraint.Property.centerX, relatedBy: NSLayoutConstraint.Narration.close, toItem: position, property: NSLayoutConstraint.Property.centerX, multiplier: 1, changeless: zero).isActive = actual NSLayoutConstraint(point: newView, property: NSLayoutConstraint.Property.centerY, relatedBy: NSLayoutConstraint.Narration.close, toItem: position, property: NSLayoutConstraint.Property.centerY, multiplier: 1, changeless: zero).isActive = actual NSLayoutConstraint(point: newView, property: NSLayoutConstraint.Property.width, relatedBy: NSLayoutConstraint.Narration.close, toItem: nil, property: NSLayoutConstraint.Property.notAnAttribute, multiplier: 1, changeless: a hundred).isActive = actual NSLayoutConstraint(point: newView, property: NSLayoutConstraint.Property.tallness, relatedBy: NSLayoutConstraint.Narration.close, toItem: nil, property: NSLayoutConstraint.Property.notAnAttribute, multiplier: 1, changeless: one hundred).isActive = actual }
2. Utilizing Ocular Format Communication
override func viewDidLoad() { fto newView = UIView() newView.backgroundColor = UIColor.reddish position.addSubview(newView) newView.translatesAutoresizingMaskIntoConstraints = mendacious fto views = ["position": position!, "newView": newView] fto horizontalConstraints = NSLayoutConstraint.constraints(withVisualFormat: "H:[position]-(<=zero)-[newView(one hundred)]", choices: NSLayoutConstraint.FormatOptions.alignAllCenterY, metrics: nil, views: views) fto verticalConstraints = NSLayoutConstraint.constraints(withVisualFormat: "V:[position]-(<=zero)-[newView(one hundred)]", choices: NSLayoutConstraint.FormatOptions.alignAllCenterX, metrics: nil, views: views) position.addConstraints(horizontalConstraints) position.addConstraints(verticalConstraints) }
override func viewDidLoad() { fto newView = UIView() newView.backgroundColor = UIColor.reddish position.addSubview(newView) newView.translatesAutoresizingMaskIntoConstraints = mendacious fto views = ["position": position!, "newView": newView] fto horizontalConstraints = NSLayoutConstraint.constraints(withVisualFormat: "H:[position]-(<=zero)-[newView(one hundred)]", choices: NSLayoutConstraint.FormatOptions.alignAllCenterY, metrics: nil, views: views) fto verticalConstraints = NSLayoutConstraint.constraints(withVisualFormat: "V:[position]-(<=zero)-[newView(a hundred)]", choices: NSLayoutConstraint.FormatOptions.alignAllCenterX, metrics: nil, views: views) NSLayoutConstraint.activate(horizontalConstraints) NSLayoutConstraint.activate(verticalConstraints) }
three. Utilizing a premix of NSLayoutConstraint initializer and Ocular Format Communication
override func viewDidLoad() { fto newView = UIView() newView.backgroundColor = UIColor.reddish position.addSubview(newView) newView.translatesAutoresizingMaskIntoConstraints = mendacious fto views = ["newView": newView] fto widthConstraints = NSLayoutConstraint.constraints(withVisualFormat: "H:[newView(one hundred)]", choices: NSLayoutConstraint.FormatOptions(rawValue: zero), metrics: nil, views: views) fto heightConstraints = NSLayoutConstraint.constraints(withVisualFormat: "V:[newView(one hundred)]", choices: NSLayoutConstraint.FormatOptions(rawValue: zero), metrics: nil, views: views) fto horizontalConstraint = NSLayoutConstraint(point: newView, property: NSLayoutConstraint.Property.centerX, relatedBy: NSLayoutConstraint.Narration.close, toItem: position, property: NSLayoutConstraint.Property.centerX, multiplier: 1, changeless: zero) fto verticalConstraint = NSLayoutConstraint(point: newView, property: NSLayoutConstraint.Property.centerY, relatedBy: NSLayoutConstraint.Narration.close, toItem: position, property: NSLayoutConstraint.Property.centerY, multiplier: 1, changeless: zero) position.addConstraints(widthConstraints) position.addConstraints(heightConstraints) position.addConstraints([horizontalConstraint, verticalConstraint]) }
override func viewDidLoad() { fto newView = UIView() newView.backgroundColor = UIColor.reddish position.addSubview(newView) newView.translatesAutoresizingMaskIntoConstraints = mendacious fto views = ["newView": newView] fto widthConstraints = NSLayoutConstraint.constraints(withVisualFormat: "H:[newView(a hundred)]", choices: NSLayoutConstraint.FormatOptions(rawValue: zero), metrics: nil, views: views) fto heightConstraints = NSLayoutConstraint.constraints(withVisualFormat: "V:[newView(a hundred)]", choices: NSLayoutConstraint.FormatOptions(rawValue: zero), metrics: nil, views: views) fto horizontalConstraint = NSLayoutConstraint(point: newView, property: NSLayoutConstraint.Property.centerX, relatedBy: NSLayoutConstraint.Narration.close, toItem: position, property: NSLayoutConstraint.Property.centerX, multiplier: 1, changeless: zero) fto verticalConstraint = NSLayoutConstraint(point: newView, property: NSLayoutConstraint.Property.centerY, relatedBy: NSLayoutConstraint.Narration.close, toItem: position, property: NSLayoutConstraint.Property.centerY, multiplier: 1, changeless: zero) NSLayoutConstraint.activate(widthConstraints) NSLayoutConstraint.activate(heightConstraints) NSLayoutConstraint.activate([horizontalConstraint, verticalConstraint]) }
override func viewDidLoad() { fto newView = UIView() newView.backgroundColor = UIColor.reddish position.addSubview(newView) newView.translatesAutoresizingMaskIntoConstraints = mendacious fto views = ["newView": newView] fto widthConstraints = NSLayoutConstraint.constraints(withVisualFormat: "H:[newView(a hundred)]", choices: NSLayoutConstraint.FormatOptions(rawValue: zero), metrics: nil, views: views) fto heightConstraints = NSLayoutConstraint.constraints(withVisualFormat: "V:[newView(a hundred)]", choices: NSLayoutConstraint.FormatOptions(rawValue: zero), metrics: nil, views: views) NSLayoutConstraint.activate(widthConstraints) NSLayoutConstraint.activate(heightConstraints) NSLayoutConstraint(point: newView, property: NSLayoutConstraint.Property.centerX, relatedBy: NSLayoutConstraint.Narration.close, toItem: position, property: NSLayoutConstraint.Property.centerX, multiplier: 1, changeless: zero).isActive = actual NSLayoutConstraint(point: newView, property: NSLayoutConstraint.Property.centerY, relatedBy: NSLayoutConstraint.Narration.close, toItem: position, property: NSLayoutConstraint.Property.centerY, multiplier: 1, changeless: zero).isActive = actual }
four. Utilizing UIView.AutoresizingMask
Line: Springs and Struts volition beryllium translated into corresponding car format constraints astatine runtime.
override func viewDidLoad() { fto newView = UIView(framework: CGRect(x: zero, y: zero, width: one hundred, tallness: a hundred)) newView.backgroundColor = UIColor.reddish position.addSubview(newView) newView.translatesAutoresizingMaskIntoConstraints = actual newView.halfway = CGPoint(x: position.bounds.midX, y: position.bounds.midY) newView.autoresizingMask = [UIView.AutoresizingMask.flexibleLeftMargin, UIView.AutoresizingMask.flexibleRightMargin, UIView.AutoresizingMask.flexibleTopMargin, UIView.AutoresizingMask.flexibleBottomMargin] }
5. Utilizing NSLayoutAnchor
override func viewDidLoad() { fto newView = UIView() newView.backgroundColor = UIColor.reddish position.addSubview(newView) newView.translatesAutoresizingMaskIntoConstraints = mendacious fto horizontalConstraint = newView.centerXAnchor.constraint(equalTo: position.centerXAnchor) fto verticalConstraint = newView.centerYAnchor.constraint(equalTo: position.centerYAnchor) fto widthConstraint = newView.widthAnchor.constraint(equalToConstant: a hundred) fto heightConstraint = newView.heightAnchor.constraint(equalToConstant: a hundred) position.addConstraints([horizontalConstraint, verticalConstraint, widthConstraint, heightConstraint]) }
override func viewDidLoad() { fto newView = UIView() newView.backgroundColor = UIColor.reddish position.addSubview(newView) newView.translatesAutoresizingMaskIntoConstraints = mendacious fto horizontalConstraint = newView.centerXAnchor.constraint(equalTo: position.centerXAnchor) fto verticalConstraint = newView.centerYAnchor.constraint(equalTo: position.centerYAnchor) fto widthConstraint = newView.widthAnchor.constraint(equalToConstant: a hundred) fto heightConstraint = newView.heightAnchor.constraint(equalToConstant: one hundred) NSLayoutConstraint.activate([horizontalConstraint, verticalConstraint, widthConstraint, heightConstraint]) }
override func viewDidLoad() { fto newView = UIView() newView.backgroundColor = UIColor.reddish position.addSubview(newView) newView.translatesAutoresizingMaskIntoConstraints = mendacious newView.centerXAnchor.constraint(equalTo: position.centerXAnchor).isActive = actual newView.centerYAnchor.constraint(equalTo: position.centerYAnchor).isActive = actual newView.widthAnchor.constraint(equalToConstant: a hundred).isActive = actual newView.heightAnchor.constraint(equalToConstant: a hundred).isActive = actual }
6. Utilizing intrinsicContentSize and NSLayoutAnchor
import UIKit people CustomView: UIView { override var intrinsicContentSize: CGSize { instrument CGSize(width: a hundred, tallness: a hundred) } } people ViewController: UIViewController { override func viewDidLoad() { fto newView = CustomView() newView.backgroundColor = UIColor.reddish position.addSubview(newView) newView.translatesAutoresizingMaskIntoConstraints = mendacious fto horizontalConstraint = newView.centerXAnchor.constraint(equalTo: position.centerXAnchor) fto verticalConstraint = newView.centerYAnchor.constraint(equalTo: position.centerYAnchor) NSLayoutConstraint.activate([horizontalConstraint, verticalConstraint]) } }
Consequence:
