请问iOS上传图片怎样设置图片路径？急！！！跪谢！！！

通过iOS的SDK上传图片时把key设置为路径的格式，如@“
/2015/06/09/0”会报错：
"The request signature we calculated does not match the signature you provided. Check your key and signing method."


应该是我的签名写的不匹配，请问我应该怎么样设置签名？现在初始化代码是这样的：
id<ALBBOSSServiceProtocol> ossService = [ALBBOSSServiceProvider getService];
    
    NSString *accessKey = @"xxx"; // 实际使用中，AK/SK不应明文保存在代码中
    NSString *secretKey = @"xxx"
    [ossService setGenerateToken:^(NSString *method, NSString *md5, NSString *type, NSString *date, NSString *xoss, NSString *resource) {
        NSString *signature = nil;
        NSString *content = [NSString stringWithFormat:@"%@\n%@\n%@\n%@\n%@%@", method, md5, type, date, xoss, resource];
        signature = [OSSTool calBase64Sha1WithData:content withKey:secretKey];
        signature = [NSString stringWithFormat:@"OSS %@:%@", accessKey, signature];
        NSLog(@"signature:%@", signature);
        return signature;
    }];
    [ossService setGlobalDefaultBucketAcl:PRIVATE];
    [ossService setGlobalDefaultBucketHostId:@"oss-cn-beijing.aliyuncs.com"];
    
    OSSBucket *ossBucket = [ossService getBucket:@"baobanimg"];
    [ossBucket setAcl:PUBLIC_READ]; // 指明该Bucket的访问权限
    [ossBucket setOssHostId:@"oss-cn-beijing.aliyuncs.com"]; // 指明该Bucket所在数据中心的域名或已经绑定Bucket的Cname域名

    [ossBucket setGenerateToken:nil]; // 指明该Bucket访问时应该采用的加签方法，若不指明则从OSSClient的全局默认设置继承；如果Bucket访问权限为Public，那么可以为null