ios - Objective-C : Is there a way to call a completion block for a method in another method?

Question

我有多个 GET API 请求方法，它们在完成时调用完成 block 。这是一个例子。

- (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，我注意到我在其他方法中重复了管理器GET 请求代码。我想创建另一种方法来处理所有请求并删除重复代码。 URL 似乎是唯一发生变化的东西。但是，有一个缺陷。我需要调用 successBlock 让方法知道请求已完成。

也许我需要完全走另一条路，做一些不同的事情。

Answer 1

您可以传递完成 block ，然后从处理所有 get 请求的 final方法中调用它们。为了简洁起见，我通常会制作将要重用的 typedef 的完成 block 。这是我的意思的一个例子(我添加了第二个示例方法，它也传递到中心 getRequestWithURLString:onSuccess:onFailure: 方法):

LLFakeManager.h

#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

LLFakeManager.m

#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

调用它的例子:

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
}];

会产生这个日志:

Here's my response object = responseObjectPassedBackHere

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