Question

IOS添加约束的时候不能使用属性和全局变量吗

Answer 1

可以.
我直接把部分代码copy了

@property (weak, nonatomic) NSLayoutConstraint *xConstraint;

@property (weak, nonatomic) NSLayoutConstraint *yConstraint;

@property (weak, nonatomic) NSLayoutConstraint *widthConstraint;

@property (weak, nonatomic) NSLayoutConstraint *heightConstraint;

在show界面的时候

[rootViewController.view addSubview:aViewController.backgroundView]; //值得注意的代码实际上就这一句, 需要先addSubView, 再添加约束

[rootViewController.view addConstraint:[NSLayoutConstraint constraintWithItem:aViewController.backgroundView attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual toItem:rootViewController.view attribute:NSLayoutAttributeTop multiplier:1 constant:0]];

[rootViewController.view addConstraint:[NSLayoutConstraint constraintWithItem:aViewController.backgroundView attribute:NSLayoutAttributeLeading relatedBy:NSLayoutRelationEqual toItem:rootViewController.view attribute:NSLayoutAttributeLeading multiplier:1 constant:0]];

[rootViewController.view addConstraint:[NSLayoutConstraint constraintWithItem:aViewController.backgroundView attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:rootViewController.view attribute:NSLayoutAttributeWidth multiplier:1 constant:0]];

[rootViewController.view addConstraint:[NSLayoutConstraint constraintWithItem:aViewController.backgroundView attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:rootViewController.view attribute:NSLayoutAttributeHeight multiplier:1 constant:0]];

Answer 2

是的！！不能使用了