Question

我创建了这样的块：

1）定义自己的完成块，

 typedef void(^myCompletion)(BOOL);

2）创建一个将完成块作为参数的方法

-(void) myMethod:(myCompletion) compblock{
//do stuff
compblock(YES);
}

3）这就是你如何使用它，

[self myMethod:^(BOOL finished) {
if(finished){
    NSLog(@"success");
}
}];

如何在块中发送数组然后从块中获取新数组？

  //here I get array of image id's and go in loop for download it all,

NSString *URLString = [NSString stringWithFormat: @"%@", requestString];
NSURL * url  = [NSURL URLWithString:URLString];
NSURLRequest * urlRequest = [NSURLRequest requestWithURL:url];

AFHTTPRequestOperation *requestOperation = [[AFHTTPRequestOperation alloc] initWithRequest:urlRequest];
requestOperation.responseSerializer = [AFImageResponseSerializer serializer];

[requestOperation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {
    userWithImage = [responseObject copy];
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
    NSLog(@"Image error: %@", error);
}];
[requestOperation start];

//here I save it to mutable array and send as completion block,

是的，我认为发送1个图像ID并在块1图像中返回会更好。在方法中，我将调用块 - 单独使用照片进行操作。那么，有可能吗？我可以使用NSNotifications做这样的事情，但是当它可以在块中时会更广泛。

Answer 1

1）定义自己的完成块

typedef void(^myCompletion)(BOOL finished, NSArray *myArray);

2）创建一个将完成块作为参数的方法

-(void)myMethod:(myCompletion)compblock {
    //do stuff
    NSArray *myArray = ...;
    compblock(YES, myArray);
}

3）这就是你如何使用它，

[self myMethod:^(BOOL finished, NSArray *myArray) {
    if (finished){
        NSLog(@"success");
    }
}];

Answer 2

如果您只想围绕AFNetworking请求编写包装器，可以编写如下方法：

- (void)downloadImageWithPath:(NSString *)path completion:(void (^)(AFHTTPRequestOperation *operation, UIImage *image, NSError *error))completion __attribute__((nonnull(2)));
{
  NSParameterAssert(completion);

  NSURL        *url        = [NSURL URLWithString:path];
  NSURLRequest *urlRequest = [NSURLRequest requestWithURL:url];

  AFHTTPRequestOperation *requestOperation = [[AFHTTPRequestOperation alloc] initWithRequest:urlRequest];
  requestOperation.responseSerializer = [AFImageResponseSerializer serializer];

  [requestOperation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {
    completion(operation, responseObject, nil);
  } failure:^(AFHTTPRequestOperation *operation, NSError *error) {
    completion(operation, nil, error);
  }];

  [requestOperation start];
}

您可以使用以下内容调用此方法：

[self downloadImageWithPath:@"http://url/to/image.jpg"
                 completion:^(AFHTTPRequestOperation *operation, UIImage *image, NSError *error) {
                   if (error) {
                     // handle error
                     return;
                   }

                   dispatch_async(dispatch_get_main_queue(), ^{
                     // Update UI with image
                   });
                 }];

如何使用参数创建块？ IOS 7

2 个答案: