當變量為控制器的實例時 也會出現(xiàn)循環(huán)引用例如abc
@interface ViewController ()<UITableViewDelegate,UITableViewDataSource>
{
UITableView *_tableView;
NSString *abc;
}

1.如果此時的block不屬于self 則直接賦值(在VC在dealloc前 必須要銷毀block回調(diào) 否則內(nèi)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];

//這樣寫block也不屬于self
void(^foo)(NSStringstr)= ^(NSString str){

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

}

2.如果此時的block屬于self 則要寫方法賦值賦值 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;

}