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目标C:是否有一种方法可以为另一个方法中的方法调用完成块?

completionhandler objective-c-blocks objective-c ios

0

Curt Rand · 技术社区 · 6 年前

我有多重 GET API请求在完成时调用完成块的方法。下面是一个例子。

- (void)getUserInfo
    onSuccess:(void (^)(id))successBlock
    onFailure:(void (^)(NSError *))failureBlock {

    NSString *urlStr = [NSString stringWithFormat:@"%@/user/", baseUrl];

    [manager GET:urlStr parameters:nil progress:nil
          success:^(NSURLSessionTask *task, id responseObject) {
              successBlock(responseObject);
          }
          failure:^(NSURLSessionTask *operation, NSError *error) {
              failureBlock(error);
          }];
}

但是,我注意到我在重复经理的话 得到 用其他方法请求代码。我想创建另一个方法来处理所有请求并删除重复的代码。URL似乎是唯一改变的东西。然而,有一个缺陷。我需要打电话给 successBlock 让方法知道请求已经完成。

也许我需要走另一条路,做些不同的事情。

2 回复 | 直到 6 年前

1

2

R4N 6 年前

您可以传递完成块,然后从处理所有GET请求的最终方法调用它们。为了简洁起见,我通常制作将被重用的typedef的完成块。这是我的意思的一个例子 getRequestWithURLString:onSuccess:onFailure: 方法:

拉法克曼

#import <Foundation/Foundation.h>

NS_ASSUME_NONNULL_BEGIN

typedef void (^_Nullable SuccessCompletionBlock)(id responseObject);
typedef void (^_Nullable FailureCompletionBlock)(NSError *error);

@interface LLFakeManager : NSObject
- (void)getUserInfoOnSuccess:(SuccessCompletionBlock)successBlock onFailure:(FailureCompletionBlock)failureBlock;
- (void)getBooksCheckedOutOnSuccess:(SuccessCompletionBlock)successBlock onFailure:(FailureCompletionBlock)failureBlock;
@end

NS_ASSUME_NONNULL_END

拉法克曼

#import "LLFakeManager.h"

@interface LLFakeManager()
- (void)getRequestWithURLString:(NSString *)urlString
                      onSuccess:(SuccessCompletionBlock)successBlock
                      onFailure:(FailureCompletionBlock)failureBlock;
@end

@implementation LLFakeManager

- (void)getUserInfoOnSuccess:(SuccessCompletionBlock)successBlock onFailure:(FailureCompletionBlock)failureBlock {
    NSString *urlStr = @"FakeUserUrlPath";
    [self getRequestWithURLString:urlStr onSuccess:successBlock onFailure:failureBlock];
}

- (void)getBooksCheckedOutOnSuccess:(SuccessCompletionBlock)successBlock onFailure:(FailureCompletionBlock)failureBlock {
    NSString *urlString = @"FakeBooksUrlPath";
    [self getRequestWithURLString:urlString onSuccess:successBlock onFailure:failureBlock];
}

// central method that will handle all the get requests
- (void)getRequestWithURLString:(NSString *)urlString
                      onSuccess:(SuccessCompletionBlock)successBlock
                      onFailure:(FailureCompletionBlock)failureBlock {
    // some fake implementation here to do your request, then use the completion block passed in from whatever other method
    if (successBlock) {
        successBlock(@"responseObjectPassedBackHere");
    }
}

@end

举个例子:

LLFakeManager *manager = [[LLFakeManager alloc] init];
[manager getUserInfoOnSuccess:^(id  _Nonnull responseObject) {
    NSLog(@"Here's my response object = %@", responseObject);
} onFailure:^(NSError * _Nonnull error) {
    // no implementation but same idea
}];

将生成此日志:

Here's my response object = responseObjectPassedBackHere

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2

0

danh 6 年前

这些块——如果它们有相同的签名——就可以沿着一系列方法传递。GET块带有一个不必要的第一个参数。这个 NSURLSessionTask * 如果要返回,则应同步返回。将其移出块签名将允许您标准化块。

用代码更容易说…

// changed this method name so it would compile

- (void)getUserInfoOnSuccess:(void (^)(id))successBlock
                   onFailure:(void (^)(NSError *))failureBlock {

    NSString *urlStr = [NSString stringWithFormat:@"%@/user/", baseUrl];

   // two things: get the task as a return value (if you need it)
   // pass the blocks directly, without nesting them in new blocks
    NSURLSessionTask *task = [manager GET: urlStr
                               parameters: nil
                                 progress: nil
                                  success: successBlock
                                  failure: failureBlock];
    // do something with the task
}

若要使此工作,请更改get方法返回类型和块签名…

- (NSURLSessionTask *)GET:(NSString *)url parameters:(id)params progress:(id)progress success:(void (^)(id))successBlock failure:(void (^)(NSError *))failureBlock {
    // return the session task created here
    return task
}