objective-c - Can I release an object created outside a block that uses it before the block is run?

Question

Can myArray be safely released before the block?

NSMutableArray *myArray = [[NSMutableArray alloc] init];
[myArray addObject:@"a"];
[myArray addObject:@"b"];

// releasing here causes an invalid object to be used inside the block?
[myArray release];

CCCallBlock *block = [CCCallBlock actionWithBlock:^{
    // print myArray contents to console
}];

[myNode runAction:block];

Answer 1

不，您不能在块之前释放数组，因为数组内部的对象和数组本身在释放调用之后将不可用，在您的块有机会保留它之前。

您可以使您的数组自动释放，在这种情况下，释放将在函数退出后发生。

NSMutableArray *myArray = [NSMutableArray array];
[myArray addObject:@"a"];
[myArray addObject:@"b"];

CCCallBlock *block = [CCCallBlock actionWithBlock:^{
    // print myArray contents to console
}];

[myNode runAction:block];

Answer 2

为了补充其他人所说的，没有autorelease，您可以在创建块后释放该数组，如果您之后不再使用该数组。

NSMutableArray *myArray = [[NSMutableArray alloc] init];
[myArray addObject:@"a"];
[myArray addObject:@"b"];

CCCallBlock *block = [CCCallBlock actionWithBlock:^{
    // print myArray contents to console
}];
[myArray release];

[myNode runAction:block];

该块在创建时保留捕获的对象（数组）。

Answer 3

不，您将在块中保留一个悬空指针。