使用NSURLSession处理HTTP错误？

Question

我正在尝试发送HTTP请求NSURLSession.它工作正常,但当服务器没有响应时,我找不到HTTP错误代码的存储位置.第三个参数completionHandler只是一个非常一般的NSError.我读了参考NSURLResponse但没有发现任何东西.

NSURLSessionDataTask *dataTask =
    [session dataTaskWithRequest:[self postRequestWithURLString:apiEntry parameters:parameters]
         completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
             if(!error) NSLog([[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]);    
         }
    ];
[dataTask resume];

Answer 1

第二个参数completionHandler是NSURLResponse,在执行HTTP请求时,通常是a NSHTTPURLResponse.所以,你通常会这样做:

NSURLSessionDataTask *dataTask = [session dataTaskWithRequest:[self postRequestWithURLString:apiEntry parameters:parameters] completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {

    // handle basic connectivity issues here

    if (error) {
        NSLog(@"dataTaskWithRequest error: %@", error);
        return;
    }

    // handle HTTP errors here

    if ([response isKindOfClass:[NSHTTPURLResponse class]]) {

        NSInteger statusCode = [(NSHTTPURLResponse *)response statusCode];

        if (statusCode != 200) {
            NSLog(@"dataTaskWithRequest HTTP status code: %d", statusCode);
            return;
        }
    }

    // otherwise, everything is probably fine and you should interpret the `data` contents

    NSLog(@"data: %@", [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]);
}];
[dataTask resume];

Answer 2

斯威夫特3:

// handle basic connectivity issues here
guard error == nil else {
    print("Error: ", error!)
    return
}

// handle HTTP errors here
if let httpResponse = response as? HTTPURLResponse {
    let statusCode = httpResponse.statusCode

    if (statusCode != 200) {
        print ("dataTaskWithRequest HTTP status code:", statusCode)
        return;
    } 
}

if let data = data {
    // here, everything is probably fine and you should interpret the `data` contents
}