加这个方法就好了.....

- (YTKRequestSerializerType)requestSerializerType
{
    return YTKRequestSerializerTypeJSON;
}

之前没说清楚 我是这样操作的 先继承YTKRequest类

@interface QH_Request : YTKRequest

@end

然后在.m文件中
#import "QH_Request.h"

@implementation QH_Request

-(NSDictionary<NSString *,NSString *> *)requestHeaderFieldValueDictionary {
    
    NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];
    NSString *token = [userDefaults objectForKey:@"token"];
    
    return @{
             @"Authorization": [NSString stringWithFormat:@"Bearer %@",token],
             //             @"content-Type": @"application/json",
             //             @"charset": @"UTF-8",
             //             @"Cache-Control": @"no-cache",
             };
}

- (YTKRequestSerializerType)requestSerializerType
{
    return YTKRequestSerializerTypeJSON;
}

@end