NSOperationQueue* queue = [[ NSOperationQueue alloc ] init];
queue.maxConcurrentOperationCount = 1;
NSOperation* someOperation = [NSBlockOperation blockOperationWithBlock:^(void) { NSLog(@"Done.");}];
if (queue.operations.count != 0)
[someOperation addDependency: queue.operations.lastObject];
你也可以簡單地類別添加到您的NSOperationQueue:
@interface NSOperationQueue (FIFOQueue)
- (void)addOperationAfterLast:(NSOperation *)op;
@end
@implementation NSOperationQueue (FIFOQueue)
- (void)addOperationAfterLast:(NSOperation *)op
{
if (self.maxConcurrentOperationCount != 1)
self.maxConcurrentOperationCount = 1;
NSOperation* lastOp = self.operations.lastObject;
if (lastOp != nil)
[op addDependency: lastOp];
[self addOperation:op];
}
@end
,並使用[隊列addOperationAfterLast:myOperation。
由於FOT的答案,但我不得不調用completionHandler();.我不知道如何用你的方法做到這一點 –