IOS学习 autolayout 动画 与文件夹拖拽截图

@interface
ViewController ()

@property (weak,
nonatomic) IBOutlet
UIView *redView;

@property (weak,
nonatomic) IBOutlet
NSLayoutConstraint *redTop;
//绑定约束

@end

@implementation ViewController

- (void)viewDidLoad {

[super
viewDidLoad];

// Do any additional setup after loading the view, typically from a nib.

}

-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent
*)event{

//只是修改约束

self.redTop.constant +=
50;

[UIView
animateWithDuration:0.5
animations:^{

//调用这个方法，可以刷新View上所有约束

[self.view
layoutIfNeeded];

}];

}