小编kal*_*lax的帖子

以编程方式使用自动布局约束

我正在尝试以编程方式在我的iOS应用中使用autolayout.我有一个简单的视图控制器与此初始化代码

UIView *innerView = [[UIView alloc] initWithFrame:self.view.bounds];

UIButton *button1 = [UIButton buttonWithType:UIButtonTypeRoundedRect];
[button1 setFrame:CGRectMake(50, 50, 150, 50)];
[button1 setTitle:@"button1" forState:UIControlStateNormal];

UIButton *button2 = [UIButton buttonWithType:UIButtonTypeRoundedRect];
[button2 setFrame:CGRectMake(250, 50, 150, 50)];
[button2 setTitle:@"button2" forState:UIControlStateNormal];

[innerView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"|[button1][button2(==button1)]|" options:NSLayoutFormatAlignAllBaseline metrics:0 views:NSDictionaryOfVariableBindings(button1, button2)]];

[innerView addSubview:button1];
[innerView addSubview:button2];
[self.view addSubview:innerView];

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但是当我试图运行它时,我收到了这个错误:

Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Unable to parse constraint format: 
Unable to interpret '|' character, because the related view doesn't have a superview 
|[button1][button2(==button1)]| 
          ^'

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它出什么问题了？

当我试图移除管道时constraintsWithVisualFormat,我收到此警告: