我有以下代码:
[[AHPinterestAPIClient sharedClient] getPath:requestURLPath parameters:nil
success:^(AFHTTPRequestOperation *operation, id response) {
[weakSelf.backgroundQueue_ addOperationWithBlock:^{
[self doSomeHeavyComputation];
[[NSOperationQueue mainQueue] addOperationWithBlock:^{
[weakSelf.collectionView_ setContentOffset:CGPointMake(0, 0)];
[weakSelf.collectionView_ reloadData];
[weakSelf.progressHUD_ hide:YES];
[[NSNotificationCenter defaultCenter] performSelector:@selector(postNotificationName:object:) withObject:@"UIScrollViewDidStopScrolling" afterDelay:0.3];
[weakSelf.progressHUD_ hide:YES];
}];
}];
}
failure:^(AFHTTPRequestOperation *operation, NSError *error) {
[weakSelf.progressHUD_ hide:YES];
[weakSelf.collectionView_.pullToRefreshView stopAnimating];
NSLog(@"Error fetching user data!");
NSLog(@"%@", error);
}];
出于某种原因,这在 iOS 5 中运行得很好,但在 iOS 6 中却不行(它会崩溃)。现在我不会询问有关 iOS 6 的问题,因为它仍处于 NDA 状态。我想知道的是,上面的代码是否有错误?如果是的话我该如何修复它。
如果我将代码放在 mainQueue 之外的 block 内,那就没问题了。 我在这里想做的是仅在 [self doSomeHeavyComputation] 完成后才执行 NSOperationQueue mainQueue 。那么这是一个依赖项,我应该如何添加这个依赖项?
更新:
这是崩溃日志(如果有帮助的话):
最佳答案
建议在 block 中“展开”弱引用,因此请尝试以下操作:
__weak id weakSelf = self;
[client getPath:path parameters:nil success:^(id op, id response) {
id strongSelf = weakSelf;
if (strongSelf == nil) return;
__weak id internalWeakSelf = strongSelf;
[strongSelf.backgroundQueue_ addOperationWithBlock:^{
id internalStrongSelf = internalWeakSelf;
if (internalStrongSelf == nil) return;
[internalStrongSelf doSomeHeavyComputation];
__weak id internalInternalWeakSelf = internalStrongSelf;
[[NSOperationQueue mainQueue] addOperationWithBlock:^{
id internalInternalStrongSelf = internalInternalWeakSelf;
if (internalInternalStrongSelf == nil) return;
[internalInternalStrongSelf reloadCollectionView];
}];
}];
}
failure:^(id op, NSError *error) {
id strongSelf = weakSelf;
if (strongSelf == nil) return;
[strongSelf stopProgress];
NSLog(@"Error fetching user data: %@", error);
}];
关于iphone - NSOperationQueue、weakSelf 和 block 的问题,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/12470820/