我收到警告：

Implicit conversion loses integer precision: ‘NSUInteger’ (aka ‘unsigned long’) to ‘CC_LONG’ (aka ‘unsigned int’)

尝试在CC_SHA1方法中传递：data.length.

data.length是NSUInteger

CC_SHA1方法定义是：

extern unsigned char *CC_SHA1(const void *data,CC_LONG len,unsigned char *md)

其中CC_LONG是32位无符号整数.

如何更改它以使用CC_LONG64？

typedef uint64_t CC_LONG64;

这是我得到上述警告的转换方法：

+(NSString*)sha1:(NSString*)input
{
    const char *cstr = [input cStringUsingEncoding:NSUTF8StringEncoding];
    NSData *data = [NSData dataWithBytes:cstr length:input.length];

    uint8_t digest[CC_SHA1_DIGEST_LENGTH];

    CC_SHA1(data.bytes,data.length,digest);

    NSMutableString* output = [NSMutableString stringWithCapacity:CC_SHA1_DIGEST_LENGTH * 2];

    for(NSInteger i = 0; i < CC_SHA1_DIGEST_LENGTH; i++)
        [output appendFormat:@"%02x",digest[i]];

    return output;

}