我的代码非常简单。我需要一个接一个地堆叠我的 View 。在 self.view 中添加 20 px 空间的两个 View
- (void)viewDidLoad {
[super viewDidLoad];
UILabel *label = [[UILabel alloc] init];
[label setTranslatesAutoresizingMaskIntoConstraints:NO];
[label.layer setBorderWidth:1.f];
[label.layer setBorderColor:[[UIColor grayColor] CGColor]];
[label setText:@"label1"];
[self.view addSubview:label];
NSLayoutConstraint *yConstraint =[NSLayoutConstraint
constraintWithItem:label
attribute:NSLayoutAttributeTop
relatedBy:NSLayoutRelationEqual
toItem:label.superview
attribute:NSLayoutAttributeTop
multiplier:1.f
constant:20];
[label.superview addConstraint:yConstraint];
NSLayoutConstraint *width =[NSLayoutConstraint
constraintWithItem:label
attribute:NSLayoutAttributeWidth
relatedBy:NSLayoutRelationEqual
toItem:label.superview
attribute:NSLayoutAttributeWidth
multiplier:1.f
constant:0];
[label.superview addConstraint:width];
NSLayoutConstraint *centerX =[NSLayoutConstraint
constraintWithItem:label
attribute:NSLayoutAttributeCenterX
relatedBy:NSLayoutRelationEqual
toItem:label.superview
attribute:NSLayoutAttributeCenterX
multiplier:1.0
constant:0];
[label.superview addConstraint:centerX];
NSLayoutConstraint *height =[NSLayoutConstraint
constraintWithItem:label
attribute:NSLayoutAttributeHeight
relatedBy:NSLayoutRelationEqual
toItem:nil
attribute:NSLayoutAttributeNotAnAttribute
multiplier:1.0
constant:40];
[label addConstraint:height];
UILabel *labe2 = [[UILabel alloc] init];
[labe2 setTranslatesAutoresizingMaskIntoConstraints:NO];
[labe2 setText:@"label2"];
[self.view addSubview:labe2];
yConstraint =[NSLayoutConstraint
constraintWithItem:labe2
attribute:NSLayoutAttributeTop
relatedBy:NSLayoutRelationEqual
toItem:label
attribute:NSLayoutAttributeBottom
multiplier:1.f
constant:20];
[labe2 addConstraint:yConstraint]; //Crashes here
}
带留言
2015-12-17 12:59:40.313 Testcase[16625:14518988] The view hierarchy is not prepared for the constraint: <NSLayoutConstraint:0x7ae4f990 V:[UILabel:0x7ae4ac30'label1']-(20)-[UILabel:0x7ae4f610'label2']>
When added to a view, the constraint's items must be descendants of that view (or the view itself). This will crash if the constraint needs to be resolved before the view hierarchy is assembled. Break on -[UIView(UIConstraintBasedLayout) _viewHierarchyUnpreparedForConstraint:] to debug.
2015-12-17 12:59:40.315 Testcase[16625:14518988] View hierarchy unprepared for constraint.
Constraint: <NSLayoutConstraint:0x7ae4f990 V:[UILabel:0x7ae4ac30'label1']-(20)-[UILabel:0x7ae4f610'label2']>
Container hierarchy:
<UILabel: 0x7ae4f610; frame = (0 0; 0 0); text = 'label2'; userInteractionEnabled = NO; layer = <_UILabelLayer: 0x7ae4f720>>
View not found in container hierarchy: <UILabel: 0x7ae4ac30; frame = (0 0; 0 0); text = 'label1'; userInteractionEnabled = NO; layer = <_UILabelLayer: 0x7ae4c3e0>>
That view's superview: <UIView: 0x7ae4af30; frame = (0 0; 320 480); autoresize = W+H; layer = <CALayer: 0x7ae4a610>>
请帮忙。敲了几个小时 走过this但没有帮助
最佳答案
替换这个
[labe2 addConstraint:yConstraint];
与
[self.view addConstraint:yConstraint];
关于ios - 添加 Y 约束时应用程序崩溃,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/34328992/