我想以编程方式将 UIImageView 添加到 View 并添加约束以使其垂直和水平居中。 使用 Storyboard ,它可以工作,但不能以编程方式进行。
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
var transitionImageView = UIImageView()
transitionImageView.frame.size = CGSize(width: 60, height: 68)
transitionImageView.contentMode = UIViewContentMode.ScaleToFill
var transitionImage = UIImage(named: "SoProxyLogo60pt")
transitionImageView.image = transitionImage
self.view.addSubview(transitionImageView)
// Position
let transitionImageViewConstraintCenterX = NSLayoutConstraint(item: transitionImageView, attribute: .CenterX, relatedBy: .Equal, toItem: self.view, attribute: .CenterX, multiplier: 1, constant: 0)
transitionImageViewConstraintCenterX.identifier = "Transition Image View Constraint Center X"
let transitionImageViewConstraintCenterY = NSLayoutConstraint(item: transitionImageView, attribute: .CenterY, relatedBy: .Equal, toItem: self.view, attribute: .CenterY, multiplier: 1, constant: 0)
transitionImageViewConstraintCenterY.identifier = "Transition Image View Constraint Center Y"
self.view.addConstraint(transitionImageViewConstraintCenterX)
self.view.addConstraint(transitionImageViewConstraintCenterY)
}
}
我有这些错误:
2014-10-27 14:45:18.420 transitionTest1[3438:70b] 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:0x7fbb5b210790 'Transition Image View Constraint Center X' UIImageView:0x7fbb5af682d0.centerX == UIView:0x7fbb5af674f0.centerX>,
<NSAutoresizingMaskLayoutConstraint:0x7fbb5b25eee0 h=--& v=--& UIImageView:0x7fbb5af682d0.midX == + 30>,
<NSAutoresizingMaskLayoutConstraint:0x7fbb5b258ee0 h=-&- v=-&- UIView:0x7fbb5af674f0.width == UIViewControllerWrapperView:0x7fbb5b257e20.width>,
<NSAutoresizingMaskLayoutConstraint:0x7fbb5b260840 h=-&- v=-&- UIViewControllerWrapperView:0x7fbb5b257e20.width == UINavigationTransitionView:0x7fbb5af5b020.width>,
<NSAutoresizingMaskLayoutConstraint:0x7fbb5b2612b0 h=-&- v=-&- UINavigationTransitionView:0x7fbb5af5b020.width == UILayoutContainerView:0x7fbb5af2adf0.width>,
<NSAutoresizingMaskLayoutConstraint:0x7fbb5b261d40 h=-&- v=-&- UILayoutContainerView:0x7fbb5af2adf0.width == UIWindow:0x7fbb5b251ba0.width>,
<NSAutoresizingMaskLayoutConstraint:0x7fbb5b25ff30 h=--- v=--- H:[UIWindow:0x7fbb5b251ba0(320)]>
Will attempt to recover by breaking constraint
Break on objc_exception_throw to catch this in the debugger. The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in may also be helpful.
2014-10-27 14:45:18.421 transitionTest1[3438:70b] 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:0x7fbb5b252fd0 'Transition Image View Constraint Center Y' UIImageView:0x7fbb5af682d0.centerY == UIView:0x7fbb5af674f0.centerY>,
<NSAutoresizingMaskLayoutConstraint:0x7fbb5b25f140 h=--& v=--& UIImageView:0x7fbb5af682d0.midY == + 34>,
<NSAutoresizingMaskLayoutConstraint:0x7fbb5b258f80 h=-&- v=-&- UIView:0x7fbb5af674f0.height == UIViewControllerWrapperView:0x7fbb5b257e20.height>,
<NSAutoresizingMaskLayoutConstraint:0x7fbb5b260930 h=-&- v=-&- UIViewControllerWrapperView:0x7fbb5b257e20.height == UINavigationTransitionView:0x7fbb5af5b020.height>,
<NSAutoresizingMaskLayoutConstraint:0x7fbb5b2613b0 h=-&- v=-&- UINavigationTransitionView:0x7fbb5af5b020.height == UILayoutContainerView:0x7fbb5af2adf0.height>,
<NSAutoresizingMaskLayoutConstraint:0x7fbb5b261e30 h=-&- v=-&- UILayoutContainerView:0x7fbb5af2adf0.height == UIWindow:0x7fbb5b251ba0.height>,
<NSAutoresizingMaskLayoutConstraint:0x7fbb5b262730 h=--- v=--- V:[UIWindow:0x7fbb5b251ba0(480)]>
Will attempt to recover by breaking constraint
Break on objc_exception_throw to catch this in the debugger. The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in may also be helpful.
(这里很难有一个好的布局;))
我不明白为什么这些约束不起作用,它们似乎与 Storyboard中的那些相同
最佳答案
更新到 SWIFT 3
我测试了你的代码,我发现的问题是你错过了这一行:
transitionImageView.translatesAutoresizingMaskIntoConstraints = false
此外,如果您希望图像大小为 60x68,则需要像这样为宽度和高度添加一些约束:
let constW = NSLayoutConstraint(item: transitionImageView, attribute: NSLayoutAttribute.width, relatedBy: NSLayoutRelation.equal, toItem: nil, attribute: NSLayoutAttribute.notAnAttribute, multiplier: 1, constant: 60)
let constV = NSLayoutConstraint(item: transitionImageView, attribute: NSLayoutAttribute.height, relatedBy: NSLayoutRelation.equal, toItem: nil, attribute: NSLayoutAttribute.notAnAttribute, multiplier: 1, constant: 68)
并将它们添加到您的 UIImageView
transitionImageView.addConstraint(constW)
transitionImageView.addConstraint(constV)
否则 UIImageView
将是 UIImage
大小,即使您分配了 CGSize
(因为 setTranslatesAutoresizingMaskIntoConstraints(false)
禁用您指定的 CGSize
。
所以你的 viewDidLoad()
方法可能是这样的:
override func viewDidLoad() {
super.viewDidLoad()
let transitionImageView = UIImageView()
transitionImageView.contentMode = UIViewContentMode.scaleToFill
//Don't forget this line
transitionImageView.translatesAutoresizingMaskIntoConstraints = false
let transitionImage = UIImage(named: "SoProxyLogo60pt.jpg")
transitionImageView.image = transitionImage
self.view.addSubview(transitionImageView)
// Position
let transitionImageViewConstraintCenterX = NSLayoutConstraint(item: transitionImageView, attribute: .centerX, relatedBy: .equal, toItem: self.view, attribute: .centerX, multiplier: 1, constant: 0)
transitionImageViewConstraintCenterX.identifier = "Transition Image View Constraint Center X"
let transitionImageViewConstraintCenterY = NSLayoutConstraint(item: transitionImageView, attribute: .centerY, relatedBy: .equal, toItem: self.view, attribute: .centerY, multiplier: 1, constant: 0)
transitionImageViewConstraintCenterY.identifier = "Transition Image View Constraint Center Y"
let constW = NSLayoutConstraint(item: transitionImageView, attribute: NSLayoutAttribute.width, relatedBy: NSLayoutRelation.equal, toItem: nil, attribute: NSLayoutAttribute.notAnAttribute, multiplier: 1, constant: 60)
let constV = NSLayoutConstraint(item: transitionImageView, attribute: NSLayoutAttribute.height, relatedBy: NSLayoutRelation.equal, toItem: nil, attribute: NSLayoutAttribute.notAnAttribute, multiplier: 1, constant: 68)
self.view.addConstraint(transitionImageViewConstraintCenterX)
self.view.addConstraint(transitionImageViewConstraintCenterY)
transitionImageView.addConstraint(constW) //self.view.addConstraint(constW) also works
transitionImageView.addConstraint(constV) //self.view.addConstraint(constV) also works
}
关于ios - 以编程方式自动布局不起作用,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/26589335/