Swift中AFError解析失败求助：含重音请求无法正常解码JSON

问题根源 #

当请求包含重音字符（如é、ñ、à等）时，若字符编码处理不当，会导致服务器接收到的请求格式异常，返回非合法JSON响应，最终触发ResponseSerializationFailureReason错误，提示"The given data was not valid JSON."。

具体解决步骤 #

1. 强制请求使用UTF-8编码 #

AFNetworking默认参数编码可能对重音字符支持不足，手动指定UTF-8编码确保字符正确传输：

// Objective-C
AFHTTPSessionManager *manager = [AFHTTPSessionManager manager];
manager.requestSerializer.stringEncoding = NSUTF8StringEncoding;

// Swift
let manager = AFHTTPSessionManager()
manager.requestSerializer.stringEncoding = .utf8

2. 修正请求头Content-Type设置 #

确保请求头明确指定UTF-8编码，避免服务器解析请求时出现编码偏差：

// Objective-C
[manager.requestSerializer setValue:@"application/json; charset=utf-8" forHTTPHeaderField:@"Content-Type"];

// Swift
manager.requestSerializer.setValue("application/json; charset=utf-8", forHTTPHeaderField: "Content-Type")

3. 自定义响应序列化器，强制UTF-8解码 #

部分服务器返回的响应未指定正确编码，导致AFNetworking解码失败，自定义序列化器覆盖默认逻辑：

// Objective-C
AFJSONResponseSerializer *serializer = [AFJSONResponseSerializer serializer];
serializer.acceptableContentTypes = [NSSet setWithObjects:@"application/json", @"text/json", @"text/javascript", @"text/plain", nil];
serializer.stringEncoding = NSUTF8StringEncoding;
manager.responseSerializer = serializer;

// Swift
let serializer = AFJSONResponseSerializer()
serializer.acceptableContentTypes = Set(["application/json", "text/json", "text/javascript", "text/plain"])
serializer.stringEncoding = .utf8
manager.responseSerializer = serializer

4. 调试原始响应数据定位问题 #

如果以上步骤无效，先获取原始响应数据，确认是服务器返回内容异常还是客户端解码问题：

// Objective-C
manager.responseSerializer = [AFHTTPResponseSerializer serializer];
[manager GET:urlString parameters:parameters progress:nil success:^(NSURLSessionDataTask * _Nonnull task, id  _Nullable responseObject) {
    NSData *data = (NSData *)responseObject;
    NSString *responseString = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
    NSLog(@"原始响应：%@", responseString);
    // 手动尝试解码
    NSError *error;
    id json = [NSJSONSerialization JSONObjectWithData:data options:0 error:&error];
    if (error) NSLog(@"解码错误：%@", error);
} failure:^(NSURLSessionDataTask * _Nullable task, NSError * _Nonnull error) {
    NSLog(@"请求失败：%@", error);
}];

// Swift
manager.responseSerializer = AFHTTPResponseSerializer()
manager.get(urlString, parameters: parameters, progress: nil) { task, responseObject in
    guard let data = responseObject as? Data else { return }
    if let responseString = String(data: data, encoding: .utf8) {
        print("原始响应：\(responseString)")
    }
    do {
        let json = try JSONSerialization.jsonObject(with: data)
        print("解码结果：\(json)")
    } catch {
        print("解码错误：\(error)")
    }
} failure: { task, error in
    print("请求失败：\(error)")
}

5. 排查服务器端编码处理 #

若客户端设置全部正确，需确认服务器是否支持UTF-8编码，能否正确解析带重音字符的请求参数——部分服务器默认编码非UTF-8，会导致请求解析异常并返回非JSON内容。

内容的提问来源于stack exchange，提问作者David Fdez