Question

我可以使用此方法用块替换委托： Best Technique for Replacing Delegate Methods with Blocks

我使用此方法替换委托：

// Generic Block Delegate
@interface __DelegateBlock:NSObject
typedef void (^HeapBlock)(NSInteger);
@property (nonatomic, copy) HeapBlock callbackBlock; 
@end

@implementation __DelegateBlock
@synthesize callbackBlock;
- (id) initWithBlock:(void(^)(NSInteger))callback
{
    // Init and copy Callback Block to the heap (@see accessor)
    if (self = [super init]) 
        [self setCallbackBlock:callback];
    return [self autorelease];
}
- (void) dealloc
{
    // Release the block
    [callbackBlock release], callbackBlock = nil;    
    [super dealloc];
}
- (void) alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
{
    // Return the result to the callback
    callbackBlock(buttonIndex);

    // Detach the block delegate, will decrement retain count
    SEL key = @selector(alertWithTitle:message:clickedBlock:cancelButtonTitle:otherButtonTitles:);
    objc_setAssociatedObject(alertView, key, nil, OBJC_ASSOCIATION_RETAIN);
    key = nil;

    // Release the Alert
    [alertView release];
}
@end

@implementation UIAlertView (BlocksDelegate)
+ (id) alertWithTitle:(NSString*)title
              message:(NSString*)message
         clickedBlock:(void(^)(NSInteger))buttonIndexClickedBlock
    cancelButtonTitle:(NSString*)cancelButtonTitle
    otherButtonTitles:(NSString*)otherButtonTitles
{
    // Create class to hold delegatee and copy block to heap
    DelegateBlock *delegatee = [[__DelegateBlock alloc] initWithBlock:buttonIndexClickedBlock];
    [[delegatee retain] autorelease];
    // Create delegater
    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:title 
                                                    message:message 
                                                   delegate:delegatee
                                          cancelButtonTitle:cancelButtonTitle 
                                          otherButtonTitles:otherButtonTitles, nil];

    // Attach the Delegate Block class to the Alert View, increase the retain count
    objc_setAssociatedObject(alert, _cmd, delegatee, OBJC_ASSOCIATION_RETAIN);

    // Display the alert
    [alert show];
    return alert;
}

@end

我应该使用

保留代表

// Create class to hold delegatee and copy block to heap
DelegateBlock *delegatee = [[__DelegateBlock alloc] initWithBlock:buttonIndexClickedBlock];
[[delegatee retain] autorelease];

但如何在ARC中执行此操作？

Answer 1

您无需在ARC中呼叫release，retain和autorelease。因此，您不需要在ARC中添加以下行。

[[delegatee retain] autorelease];

如何使用ARC替换委托与块

1 个答案: