NSURLSession错误中的返回值 [英] Return value in NSURLSession Error

问题描述

尝试返回responseString时出现以下错误

I get below error while trying to return responseString

不兼容的块指针类型将'NSString *(^)(NSData * __ strong，NSURLResponse * __ strong，NSError * __ strong)'发送给类型为void(^)(NSData * __ strong，NSURLResponse * __ strong，NSError的参数* __ strong)'

我从AViewController类调用它的地方

where i call it from Suppose AViewController Class

NSString *responseString=[self callAPI];

下面是我在BViewModel类中的代码:

And below is my code in BViewModel class:

-(NSString* )callAPI
{
    NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration defaultSessionConfiguration];
    NSURLSession *session = [NSURLSession sessionWithConfiguration:configuration delegate:self delegateQueue:nil];
    NSURL *url = [NSURL URLWithString:@"http://appersgroup.com/talkawalk/login.php?email=[e-mail]&password=123456&latitude=52.486245&longitude=13.327496&device_token=show"];
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url
                                                           cachePolicy:NSURLRequestUseProtocolCachePolicy
                                                       timeoutInterval:60.0];

    [request addValue:@"application/json" forHTTPHeaderField:@"Content-Type"];
    [request addValue:@"application/json" forHTTPHeaderField:@"Accept"];

    [request setHTTPMethod:@"POST"];
    /* NSDictionary *mapData = [[NSDictionary alloc] initWithObjectsAndKeys: @"TEST IOS", @"name",
     @"IOS TYPE", @"typemap",
     nil];
     NSData *postData = [NSJSONSerialization dataWithJSONObject:mapData options:0 error:&error];
     [request setHTTPBody:postData];
     */

    NSURLSessionDataTask *postDataTask = [session dataTaskWithRequest:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {

        NSString* responseString = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];

        if([responseString rangeOfString:@"nil"].location != NSNotFound)
        {
            NSString * newResponse =  [[NSString alloc] initWithData:data encoding:NSASCIIStringEncoding];

            responseString = newResponse;
        }

        NSLog(@"%@",responseString);
        NSLog(@"response %@",response);
        NSLog(@"error %@",error);

        return responseString;//adding this line give me error ? how to return value 


    }];

    [postDataTask resume];
}

推荐答案

您可以将这种方法与类似的代码块一起使用:

You can use this method with block like this :

-(void)callAPIWithCompletionHandler : (void (^) (NSString * strResponse)) completionHandler
{
    NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration defaultSessionConfiguration];
    NSURLSession *session = [NSURLSession sessionWithConfiguration:configuration delegate:self delegateQueue:nil];
    NSURL *url = [NSURL URLWithString:@"http://appersgroup.com/talkawalk/login.php?email=[e-mail]&password=123456&latitude=52.486245&longitude=13.327496&device_token=show"];
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url
                                                           cachePolicy:NSURLRequestUseProtocolCachePolicy
                                                       timeoutInterval:60.0];

    [request addValue:@"application/json" forHTTPHeaderField:@"Content-Type"];
    [request addValue:@"application/json" forHTTPHeaderField:@"Accept"];

    [request setHTTPMethod:@"POST"];
    /* NSDictionary *mapData = [[NSDictionary alloc] initWithObjectsAndKeys: @"TEST IOS", @"name",
     @"IOS TYPE", @"typemap",
     nil];
     NSData *postData = [NSJSONSerialization dataWithJSONObject:mapData options:0 error:&error];
     [request setHTTPBody:postData];
     */

    NSURLSessionDataTask *postDataTask = [session dataTaskWithRequest:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {

        NSString* responseString = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];

        if([responseString rangeOfString:@"nil"].location != NSNotFound)
        {
            NSString * newResponse =  [[NSString alloc] initWithData:data encoding:NSASCIIStringEncoding];

            responseString = newResponse;
        }

        NSLog(@"%@",responseString);
        NSLog(@"response %@",response);
        NSLog(@"error %@",error);

        completionHandler(responseString);

    }];

    [postDataTask resume];
}

调用此方法并返回如下响应:

Call this method and return response as below :

[self callAPIWithCompletionHandler:^(NSString *strResponse) {

        NSString *responseString = strResponse;
}];

假设此方法在 ViewControllerA 中实现，并且您想从 ViewControllerB 调用此方法.

Suppose this method implemented in ViewControllerA, and you want to call this from ViewControllerB.

然后在 ViewControllerB 中导入 ViewControllerA ，并在 ViewControllerB 中创建 ViewControllerA 的实例.

Then import ViewControllerA in ViewControllerB and make instance of ViewControllerA in ViewControllerB.

ViewControllerA *vcA = [[ViewControllerA alloc] init];
[vcA callAPIWithCompletionHandler:^(NSString *strResponse) {

        NSString *responseString = strResponse;
}];

这篇关于NSURLSession错误中的返回值的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！