iOS 控制器的实例 的block循环引用

当变量为控制器的实例时 也会出现循环引用例如abc
@interface ViewController ()
{
UITableView *_tableView;
NSString *abc;
}

1.如果此时的block不属于self 则直接赋值(在VC在dealloc前 必须要销毁block回调 否则内存泄漏) 例如添加在keywindow上的View：

• (void)viewDidLoad {
  [super viewDidLoad];

  AView *view = [[AView alloc] init];
  view.frame = CGRectMake(100, 100, 100, 100);
  view.backgroundColor = [UIColor redColor];
  view.abc = ^(NSString *aaa){

    abc = aaa;
  

  };
  AppDelegate *delegate = (AppDelegate *)[UIApplication sharedApplication].delegate;
  UIWindow *keywindow = delegate.window;
  [keywindow addSubview:view];
  [view removeFromSuperview];

//这样写block也不属于self
void(^foo)(NSStringstr)= ^(NSString str){

    abc = str;
};
foo(@"1111");

}

2.如果此时的block属于self 则要写方法赋值赋值 例如添加在self.view上的View：

• (void)viewDidLoad {
  [super viewDidLoad];

  __weak typeof(self) weakSelf = self;
  AView *view = [[AView alloc] init];
  view.frame = CGRectMake(100, 100, 100, 100);
  view.backgroundColor = [UIColor redColor];
  view.abc = ^(NSString *aaa){
  [weakSelf setAbc:aaa];
  };
  [self.view addSubview:view];
  }

-(void)setAbc:(NSString *)a{

abc = a;

}