1、 weak和assign的区别?
/* __unsafe_unretained（不安全的，不引用-不持有）
* 如果指针指向的对象被销毁,但是 assign 并没有把指针清空
* 不会让引用计数器+1
*/
@property (nonatomic, assign) UIView *magentaView;
/* weak 一般用于修饰控件
* 如果指针指向的对象被销毁,那么 weak 会让这个指针也清空
* ARC才有，不会让引用计数器+1
*/
@property (nonatomic, weak) UIView *redView;
//-----------------------------------------------------------
- (void)configUI {
UIView *view1 = [[UIView alloc] init];
view1.backgroundColor = [UIColor magentaColor];
[self.view addSubview:view1];
self.magentaView = view1;
UIView *view = [[UIView alloc] init];
view.backgroundColor = [UIColor redColor];
[self.view addSubview:view];
self.redView = view;
}
-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
{
_magentaView.frame = CGRectMake(50, 50, 100, 100);
_redView.frame = CGRectMake(200, 50, 100, 100);
}
