移动父视图时出现约束错误
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【中文标题】移动父视图时出现约束错误【英文标题】：Constraint Error when moving parentView 【发布时间】：2016-06-16 22:46:13 【问题描述】：我的视图设置具有以下约束：
bottomContainerViewConstraint = NSLayoutConstraint(item: containerView, attribute: .Bottom, relatedBy: .Equal, toItem: self.view, attribute: .Bottom, multiplier: 1, constant: -10)
self.view.addConstraint(bottomContainerViewConstraint!)
topContainerViewConstraint = NSLayoutConstraint(item: containerView, attribute: .Leading, relatedBy: .Equal, toItem: self.view, attribute: .Leading, multiplier: 1, constant: 10)
self.view.addConstraint(topContainerViewConstraint!)
self.view.addConstraint(NSLayoutConstraint(item: containerView, attribute: .Trailing, relatedBy: .Equal, toItem: self.view, attribute: .Trailing, multiplier: 1, constant: -10))
self.view.addConstraint(NSLayoutConstraint(item: containerView, attribute: .Top, relatedBy: .Equal, toItem: self.view, attribute: .Bottom, multiplier: 1, constant: -120))
//caption and profilepic constraints
self.view.addConstraint(NSLayoutConstraint(item: captionAndProfileImageContainerView, attribute: .Top, relatedBy: .Equal, toItem: containerView, attribute: .Top, multiplier: 1, constant: 0))
self.view.addConstraint(NSLayoutConstraint(item: captionAndProfileImageContainerView, attribute: .Leading, relatedBy: .Equal, toItem: containerView, attribute: .Leading, multiplier: 1, constant: 0))
self.view.addConstraint(NSLayoutConstraint(item: captionAndProfileImageContainerView, attribute: .Trailing, relatedBy: .Equal, toItem: containerView, attribute: .Trailing, multiplier: 1, constant: -110))
self.view.addConstraint(NSLayoutConstraint(item: captionAndProfileImageContainerView, attribute: .Bottom, relatedBy: .Equal, toItem: containerView, attribute: .Bottom, multiplier: 1, constant: 0))
self.view.addConstraintsWithFormat("H:|-8-[v0(50)]", views: profilePicImageView)
self.view.addConstraintsWithFormat("V:|-30-[v0(50)]", views: profilePicImageView)
profilePicImageView.layer.cornerRadius = 25
profilePicImageView.layer.masksToBounds = true
self.view.addConstraint(NSLayoutConstraint(item: captionTextView, attribute: .Top, relatedBy: .Equal, toItem: captionAndProfileImageContainerView, attribute: .Top, multiplier: 1, constant: 0))
self.view.addConstraint(NSLayoutConstraint(item: captionTextView, attribute: .Leading, relatedBy: .Equal, toItem: profilePicImageView, attribute: .Trailing, multiplier: 1, constant: 8))
self.view.addConstraint(NSLayoutConstraint(item: captionTextView, attribute: .Trailing, relatedBy: .Equal, toItem: captionAndProfileImageContainerView, attribute: .Trailing, multiplier: 1, constant: 0))
self.view.addConstraint(NSLayoutConstraint(item: captionTextView, attribute: .Bottom, relatedBy: .Equal, toItem: captionAndProfileImageContainerView, attribute: .Bottom, multiplier: 1, constant: 0))
//likes and comments and divider
self.view.addConstraint(NSLayoutConstraint(item: commentAndLikesContainerView, attribute: .Top, relatedBy: .Equal, toItem: containerView, attribute: .Top, multiplier: 1, constant: 0))
self.view.addConstraint(NSLayoutConstraint(item: commentAndLikesContainerView, attribute: .Leading, relatedBy: .Equal, toItem: captionAndProfileImageContainerView, attribute: .Trailing, multiplier: 1, constant: 0))
self.view.addConstraint(NSLayoutConstraint(item: commentAndLikesContainerView, attribute: .Trailing, relatedBy: .Equal, toItem: containerView, attribute: .Trailing, multiplier: 1, constant: 0))
self.view.addConstraint(NSLayoutConstraint(item: commentAndLikesContainerView, attribute: .Bottom, relatedBy: .Equal, toItem: containerView, attribute: .Bottom, multiplier: 1, constant: 0))
self.view.addConstraint(NSLayoutConstraint(item: voteUpButton, attribute: .Top, relatedBy: .Equal, toItem: commentAndLikesContainerView, attribute: .Top, multiplier: 1, constant: 0))
self.view.addConstraint(NSLayoutConstraint(item: voteUpButton, attribute: .Leading, relatedBy: .Equal, toItem: commentButton, attribute: .Trailing, multiplier: 1, constant: 0))
self.view.addConstraint(NSLayoutConstraint(item: likesLabel, attribute: .Top, relatedBy: .Equal, toItem: voteUpButton, attribute: .Bottom, multiplier: 1, constant: -5.5))
self.view.addConstraint(NSLayoutConstraint(item: likesLabel, attribute: .Leading, relatedBy: .Equal, toItem: voteUpButton, attribute: .Leading, multiplier: 1, constant: 11.5))
self.view.addConstraint(NSLayoutConstraint(item: voteDownButton, attribute: .Top, relatedBy: .Equal, toItem: likesLabel, attribute: .Bottom, multiplier: 1, constant: 0))
self.view.addConstraint(NSLayoutConstraint(item: voteDownButton, attribute: .Leading, relatedBy: .Equal, toItem: likesLabel, attribute: .Leading, multiplier: 1, constant: -11.5))
self.view.addConstraint(NSLayoutConstraint(item: commentButton, attribute: .Top, relatedBy: .Equal, toItem: commentAndLikesContainerView, attribute: .Top, multiplier: 1, constant: 37))
self.view.addConstraint(NSLayoutConstraint(item: commentButton, attribute: .Leading, relatedBy: .Equal, toItem: commentAndLikesContainerView, attribute: .Leading, multiplier: 1, constant: 10))
self.view.addConstraint(NSLayoutConstraint(item: commentLabel, attribute: .Top, relatedBy: .Equal, toItem: commentButton, attribute: .Top, multiplier: 1, constant: 7.5))
self.view.addConstraint(NSLayoutConstraint(item: commentLabel, attribute: .Leading, relatedBy: .Equal, toItem: commentButton, attribute: .Leading, multiplier: 1, constant: 12.5))
现在我正在尝试更改 bottomContainerViewConstraint 和 topContainerViewConstraint 并使用以下代码将 containerView 位置移动到屏幕顶部：
func moveViewFromBottomToTop(viewToBeMoved : UIView, bottomConstraint : NSLayoutConstraint, topConstraint : NSLayoutConstraint, completionHandler: (loaded: Bool, dataNil: Bool) -> ()) -> ()
if (topConstraint.constant > (-self.view.frame.height))
topConstraint.constant = -self.view.frame.height
bottomConstraint.constant = -self.view.frame.height + 120
UIView.animateWithDuration(0.5, delay: 0, options: UIViewAnimationOptions.CurveEaseOut, animations:
self.view.layoutIfNeeded()
, completion: (completed) in
)
代码中提到的所有其他视图都是containerView的子视图。我收到以下错误：
2016-06-16 23:35:33.282 City[18312:474417] 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.
(
"<NSLayoutConstraint:0x7f95e1577e30 UIView:0x7f95e1566670.bottom == UIView:0x7f95e161a710.bottom - 547>",
"<NSLayoutConstraint:0x7f95e159eb40 UIView:0x7f95e1566670.top == UIView:0x7f95e161a710.bottom - 120>",
"<NSLayoutConstraint:0x7f95e15c1160 UIView:0x7f95e15667e0.top == UIView:0x7f95e1566670.top>",
"<NSLayoutConstraint:0x7f95e1502ed0 UIView:0x7f95e15667e0.bottom == UIView:0x7f95e1566670.bottom>",
"<NSLayoutConstraint:0x7f95e15163b0 UITextView:0x7f95e2107c00.top == UIView:0x7f95e15667e0.top>",
"<NSLayoutConstraint:0x7f95e1552b50 UITextView:0x7f95e2107c00.bottom == UIView:0x7f95e15667e0.bottom>"
)
Will attempt to recover by breaking constraint
<NSLayoutConstraint:0x7f95e159eb40 UIView:0x7f95e1566670.top == UIView:0x7f95e161a710.bottom - 120>
我不明白为什么这是个问题。这些约束不应该只是自动调整，因为它们都是 containerView 的子视图，并且所有约束都是相对于 containerView 的吗？
【问题讨论】：
【参考方案1】：不要忘记如果你使用代码约束，你需要禁用 translateAutoResizingMaskIntoConstraints
例如：
captionAndProfileImageContainerView.translateAutoresizingMaskIntoConstraints = false
captionTextView.translateAutoresizingMaskIntoConstraints = false
对所有子视图都这样做
【讨论】：
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