SB中拖好空间,让后分别在,Pin,Align,Resolve Auto Layout Issues三个面板中设置好约束就好了。
用存代码的方式给控件添加约束,完成自动布局:
利用NSLayoutConstraint类创建具体的约束对象。apple提供了两种方法
- (void)addConstraint:(NSLayoutConstraint *)constraint;
- (void)addConstraints:(NSArray *)constraints;
在控制器的-viewDidLoad方法里
- (void)viewDidLoad {
[super viewDidLoad];
UIView *subView = [UIView allc] initWithFrame:CGRectMake(100,200,100,100)];
subView.backgroundColor = [UIColor lightGray];
//设置 autoresizing 无效 不认会把我们的约束无效化
subView.translatesAutoresizingMaskIntoConstraints = NO;
[self.view addSubview:subView];
//距离父视图左边的距离 约束
NSLayoutConstraint *leftConstraint = [NSLayoutConstraint constraintWithItem:subView attribute:NSLayoutAttributeLeft relatedBy:NSLayoutRelatinEqual toItem:nil attribute:NSLayoutAttributeLeft multiplier:1.0 constant:100];
//距离父视图顶部的距离 约束
NSLayoutConstraint *topConstraint = [NSLayoutConstraint constraintWithItem:subView attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelatinEqual toItem:nil attribute:NSLayoutAttributeTop multiplier:1.0 constant:100];
//subView 的宽带约束
NSLayoutConstraint *widthConstraint = [NSLayoutConstraint constraintWithItem:subView attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelatinEqual toItem:nil attribute:NSLayoutAttributeNotAnAtribute multiplier:0.0 constant:100];
//subView 的高带约束
NSLayoutConstraint *heightConstraint = [NSLayoutConstraint constraintWithItem:subView attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelatinEqual toItem:nil attribute:NSLayoutAttributeNotAnAtribute multiplier:0.0 constant:100];
[self.view addConstraint:leftConstraint];
[self.view addConstraint:TopConstraint];
[self.view addConstraint:heightConstraint];
[self.view addConstraint:widthConstraint];
}