iphone-如何在塊中獲取實體變量？

如何在塊中獲取實體變量？

訪問block中的實體變量。但是在block中得到EXC_BAC_ACCESS。工程裡沒用ARC。

.h file

@interface ViewController : UIViewController{
    int age; // an instance variable
}



.m file

typedef void(^MyBlock) (void);

MyBlock bb;

@interface ViewController ()

- (void)foo;

@end

@implementation ViewController

- (void)viewDidLoad{
    [super viewDidLoad];

    __block ViewController *aa = self;

    bb = ^{
        NSLog(@"%d", aa->age);// EXC_BAD_ACCESS here
        // NSLog(@"%d", age); // I also tried this code, didn't work
    };

    Block_copy(bb);

    UIButton *btn = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    btn.frame = CGRectMake(10, 10, 200, 200);
    [btn setTitle:@"Tap Me" forState:UIControlStateNormal];
    [self.view addSubview:btn];

    [btn addTarget:self action:@selector(foo) forControlEvents:UIControlEventTouchUpInside];
}

- (void)foo{
    bb();
}

@end

為什麼會這樣？

最佳回答：

你訪問的block塊已經在堆棧上分配了；你需要為塊指定bb。bb也需要放在類的實體變量中。

  bb= Block_copy(bb);