SWIFT |添加约束编程 [英] SWIFT | Adding constraints programmatically

问题描述

我想摸不着头脑，因为上周没有去任何一步。好了，所以我需要应用一些的限制 编程的在斯威夫特到的UIView 使用此code：

I'm trying to figure this out since last week without going any step further. Ok, so I need to apply some constraints programmatically in Swift to a UIView using this code:

var new_view:UIView! = UIView(frame: CGRectMake(0, 0, 100, 100));
    new_view.backgroundColor = UIColor.redColor();
    view.addSubview(new_view);


    var constX:NSLayoutConstraint = NSLayoutConstraint(item: new_view, attribute: NSLayoutAttribute.CenterX, relatedBy: NSLayoutRelation.Equal, toItem: self.view, attribute: NSLayoutAttribute.CenterX, multiplier: 1, constant: 0);
    self.view.addConstraint(constX);
    //
    //
    var constY:NSLayoutConstraint = NSLayoutConstraint(item: new_view, attribute: NSLayoutAttribute.CenterY, relatedBy: NSLayoutRelation.Equal, toItem: self.view, attribute: NSLayoutAttribute.CenterY, multiplier: 1, constant: 0);
    self.view.addConstraint(constY);
    //
    //
    var constW:NSLayoutConstraint = NSLayoutConstraint(item: new_view, attribute: NSLayoutAttribute.Width, relatedBy: NSLayoutRelation.Equal, toItem: new_view, attribute: NSLayoutAttribute.Width, multiplier: 1, constant: 0);
    self.view.addConstraint(constW);
    //
    //
    var constH:NSLayoutConstraint = NSLayoutConstraint(item: new_view, attribute: NSLayoutAttribute.Height, relatedBy: NSLayoutRelation.Equal, toItem: new_view, attribute: NSLayoutAttribute.Height, multiplier: 1, constant: 0);
    self.view.addConstraint(constH);

不过X code回到这个奇怪的输出：

But Xcode returns this weird output:

2014-10-03 09:48:12.657 Test[35088:2454916] Unable to simultaneously satisfy constraints.  Probably at least one of the constraints in the following list is one you don't want. Try this: (1) look at each constraint and try to figure out which you don't expect; (2) find the code that added the unwanted constraint or constraints and fix it. (Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints) 
(
"<NSLayoutConstraint:0x7fa4ea446830 UIView:0x7fa4ea429290.centerX == UIView:0x7fa4ea4470f0.centerX>",
"<NSAutoresizingMaskLayoutConstraint:0x7fa4ea4516c0 h=--& v=--& UIView:0x7fa4ea429290.midX == + 50>",
"<NSLayoutConstraint:0x7fa4ea452830 'UIView-Encapsulated-Layout-Width' H:[UIView:0x7fa4ea4470f0(375)]>",
"<NSAutoresizingMaskLayoutConstraint:0x7fa4ea446db0 h=-&- v=-&- 'UIView-Encapsulated-Layout-Left' H:|-(0)-[UIView:0x7fa4ea4470f0]   (Names: '|':UIWindow:0x7fa4ea444b20 )>"
)

Will attempt to recover by breaking constraint <NSLayoutConstraint:0x7fa4ea446830 UIView:0x7fa4ea429290.centerX == UIView:0x7fa4ea4470f0.centerX>

Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger. The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in
<UIKit/UIView.h> may also be helpful.

2014-10-03 09:48:12.658 Test[35088:2454916] Unable to simultaneously satisfy constraints.  Probably at least one of the constraints in the following list is one you don't want. Try this: (1) look at each constraint and try to figure out which you don't expect; (2) find the code that added the unwanted constraint or constraints and fix it. (Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints)
(
"<NSLayoutConstraint:0x7fa4ea44d160 UIView:0x7fa4ea429290.centerY == UIView:0x7fa4ea4470f0.centerY>",
"<NSAutoresizingMaskLayoutConstraint:0x7fa4ea451b30 h=--& v=--& UIView:0x7fa4ea429290.midY == + 50>",
"<NSLayoutConstraint:0x7fa4ea44cf00 'UIView-Encapsulated-Layout-Height' V:[UIView:0x7fa4ea4470f0(667)]>",
"<NSAutoresizingMaskLayoutConstraint:0x7fa4ea452700 h=-&- v=-&- 'UIView-Encapsulated-Layout-Top' V:|-(0)-[UIView:0x7fa4ea4470f0]  (Names: '|':UIWindow:0x7fa4ea444b20 )>"
)

Will attempt to recover by breaking constraint <NSLayoutConstraint:0x7fa4ea44d160 UIView:0x7fa4ea429290.centerY == UIView:0x7fa4ea4470f0.centerY>

Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger. The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKit/UIView.h> may also be helpful.

你能帮助我吗？
非常感谢

Can you help me? Thanks a lot

推荐答案

你打算有一个平方的UIView 中的宽度：100 的和的身高：100 的中心里面的的UIView 的的UIViewController ？如果是这样，你可以尝试以下6自动布局codeS之一：

Do you plan to have a squared UIView of width: 100 and Height: 100 centered inside the UIView of an UIViewController? If so, you may try one of the 6 following Auto Layout codes:

override func viewDidLoad() {
    super.viewDidLoad()

    let newView = UIView()
    newView.backgroundColor = UIColor.redColor()
    newView.translatesAutoresizingMaskIntoConstraints = false
    view.addSubview(newView)

    let horizontalConstraint = NSLayoutConstraint(item: newView, attribute: NSLayoutAttribute.CenterX, relatedBy: NSLayoutRelation.Equal, toItem: view, attribute: NSLayoutAttribute.CenterX, multiplier: 1, constant: 0)
    view.addConstraint(horizontalConstraint)

    let verticalConstraint = NSLayoutConstraint(item: newView, attribute: NSLayoutAttribute.CenterY, relatedBy: NSLayoutRelation.Equal, toItem: view, attribute: NSLayoutAttribute.CenterY, multiplier: 1, constant: 0)
    view.addConstraint(verticalConstraint)

    let widthConstraint = NSLayoutConstraint(item: newView, attribute: NSLayoutAttribute.Width, relatedBy: NSLayoutRelation.Equal, toItem: nil, attribute: NSLayoutAttribute.NotAnAttribute, multiplier: 1, constant: 100)
    view.addConstraint(widthConstraint)

    let heightConstraint = NSLayoutConstraint(item: newView, attribute: NSLayoutAttribute.Height, relatedBy: NSLayoutRelation.Equal, toItem: nil, attribute: NSLayoutAttribute.NotAnAttribute, multiplier: 1, constant: 100)
    view.addConstraint(heightConstraint)
}

---

2。混合式（ NSLayoutConstraint +可视格式语言）

---

2. Mixed style (NSLayoutConstraint + Visual Format Language)

override func viewDidLoad() {
    super.viewDidLoad()

    let newView = UIView()
    newView.backgroundColor = UIColor.redColor()
    newView.translatesAutoresizingMaskIntoConstraints = false
    view.addSubview(newView)

    let horizontalConstraint = NSLayoutConstraint(item: newView, attribute: NSLayoutAttribute.CenterX, relatedBy: NSLayoutRelation.Equal, toItem: view, attribute: NSLayoutAttribute.CenterX, multiplier: 1, constant: 0)
    view.addConstraint(horizontalConstraint)

    let verticalConstraint = NSLayoutConstraint(item: newView, attribute: NSLayoutAttribute.CenterY, relatedBy: NSLayoutRelation.Equal, toItem: view, attribute: NSLayoutAttribute.CenterY, multiplier: 1, constant: 0)
    view.addConstraint(verticalConstraint)

    let views = ["newView": newView]

    let widthConstraints = NSLayoutConstraint.constraintsWithVisualFormat("H:[newView(100)]", options: NSLayoutFormatOptions(rawValue: 0), metrics: nil, views: views)
    view.addConstraints(widthConstraints)

    let heightConstraints = NSLayoutConstraint.constraintsWithVisualFormat("V:[newView(100)]", options: NSLayoutFormatOptions(rawValue: 0), metrics: nil, views: views)
    view.addConstraints(heightConstraints)
}

---

3。视觉格式语言风格

override func viewDidLoad() {
    super.viewDidLoad()

    let newView = UIView()
    newView.backgroundColor = UIColor.redColor()
    newView.translatesAutoresizingMaskIntoConstraints = false
    view.addSubview(newView)

    let views = ["view": view, "newView": newView]
    let horizontalConstraints = NSLayoutConstraint.constraintsWithVisualFormat("H:[view]-(<=0)-[newView(100)]", options: NSLayoutFormatOptions.AlignAllCenterY, metrics: nil, views: views)
    view.addConstraints(horizontalConstraints)
    let verticalConstraints = NSLayoutConstraint.constraintsWithVisualFormat("V:[view]-(<=0)-[newView(100)]", options: NSLayoutFormatOptions.AlignAllCenterX, metrics: nil, views: views)
    view.addConstraints(verticalConstraints)
}

---

4。 UIViewAutoresizing 风格

override func viewDidLoad() {
    super.viewDidLoad()

    let newView = UIView(frame: CGRect(x: 0, y: 0, width: 100, height: 100))
    newView.backgroundColor = UIColor.redColor()
    newView.translatesAutoresizingMaskIntoConstraints = true
    view.addSubview(newView)

    newView.center = CGPoint(x: view.bounds.midX, y: view.bounds.midY)
    newView.autoresizingMask = [UIViewAutoresizing.FlexibleLeftMargin, UIViewAutoresizing.FlexibleRightMargin, UIViewAutoresizing.FlexibleTopMargin, UIViewAutoresizing.FlexibleBottomMargin]
}

---

5。 NSLayoutAnchor 风格（需要iOS 9 +）

---

5. NSLayoutAnchor style (requires iOS 9+)

override func viewDidLoad() {
    super.viewDidLoad()

    let newView = UIView()
    newView.backgroundColor = UIColor.redColor()
    newView.translatesAutoresizingMaskIntoConstraints = false
    view.addSubview(newView)

    let horizontalConstraint = newView.centerXAnchor.constraintEqualToAnchor(view.centerXAnchor)
    let verticalConstraint = newView.centerYAnchor.constraintEqualToAnchor(view.centerYAnchor)
    let widthConstraint = newView.widthAnchor.constraintEqualToAnchor(nil, constant: 100)
    let heightConstraint = newView.heightAnchor.constraintEqualToAnchor(nil, constant: 100)
    NSLayoutConstraint.activateConstraints([horizontalConstraint, verticalConstraint, widthConstraint, heightConstraint])
}

---

6。子类风格

import UIKit

class CustomView: UIView {
    override func intrinsicContentSize() -> CGSize {
        return CGSize(width: 100, height: 100)
    }
}

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        let newView = CustomView()
        newView.backgroundColor = .redColor()
        newView.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview(newView)

        // Auto layout code using anchors (iOS9+)
        let horizontalConstraint = newView.centerXAnchor.constraintEqualToAnchor(view.centerXAnchor)
        let verticalConstraint = newView.centerYAnchor.constraintEqualToAnchor(view.centerYAnchor)
        NSLayoutConstraint.activateConstraints([horizontalConstraint, verticalConstraint])
    }

}

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