一、AFN网络请求常见问题

1. Request failed: unauthorized (401)

+ (NSString *)dictionaryToJSONString:(NSDictionary *)dictionary 
{
    NSError *error = nil;
    NSData *jsonData = [NSJSONSerialization dataWithJSONObject:dictionary options:NSJSONWritingPrettyPrinted error:&error];
    NSString *jsonString = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];
    return jsonString;
}


+ (NSString *)arrayToJSONString:(NSArray *)array
 {
    NSError *error = nil;
    NSData *jsonData = [NSJSONSerialization dataWithJSONObject:array options:NSJSONWritingPrettyPrinted error:&error];
    NSString *jsonString = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];
}


// 字符串转Data
NSString *str =@"jesfds"; 
NSData *data =[str dataUsingEncoding:NSUTF8StringEncoding];
// NSData转NSString
NSString *result  =[[ NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];

// data 转char
NSData *data; 
char *test=[data bytes]; 

// char 转data 
byte* tempData = malloc(sizeof(byte)*16); 
NSData *content=[NSData dataWithBytes:tempData length:16];

2. 3840

错误信息如下:

Error Domain=NSCocoaErrorDomain Code=3840 "The operation couldn’t be completed. (Cocoa error 3840.)" (JSON text did not start with array or object and option to allow fragments not set.) UserInfo=0x9152780 {NSDebugDescription=JSON text did not start with array or object and option to allow fragments not set.}

错因：接口返回的是字符串，客户端却以JSON类型接收。

解决方案如下:

 sessionManager.responseSerializer = [AFHTTPResponseSerializer serializer];

3. -1016

在进行网络请求时出现-1016 是因为只支持text/json，application/json，text/javascript。
解决方案如下：

manager.responseSerializer.acceptableContentTypes = [NSSet setWithObjects:@"text/html",@"application/json",nil];

3. code 和 statusCode

• 获取statusCode

failure:^(NSURLSessionDataTask * _Nullable task, NSError * _Nonnull error) {
        NSHTTPURLResponse *response = (NSHTTPURLResponse *)task.response;
        NSInteger statusCode = [response statusCode];
    }];
}