iOS字符串加密至MD5&及获取文件MD5

　　iOS 字符串加密至MD5

#import <CommonCrypto/CommonDigest.h>

+ (NSString *) md5:(NSString *)str
{
const char *cStr = [str UTF8String];
unsigned char result[16];
CC_MD5( cStr, strlen(cStr), result );
return [NSString stringWithFormat:@"%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X",
result[0], result[1], result[2], result[3],
result[4], result[5], result[6], result[7],
result[8], result[9], result[10], result[11],
result[12], result[13], result[14], result[15]
];
}

　　iOS处理大文件检测MD5的代码 

+(NSString*)fileMD5:(NSString*)path
{
NSFileHandle *handle = [NSFileHandle fileHandleForReadingAtPath:path];
if( handle== nil ) return @"ERROR GETTING FILE MD5"; // file didnt exist

CC_MD5_CTX md5;

CC_MD5_Init(&md5);

BOOL done = NO;
while(!done)
{
NSData* fileData = [handle readDataOfLength: CHUNK_SIZE ];
CC_MD5_Update(&md5, [fileData bytes], [fileData length]);
if( [fileData length] == 0 ) done = YES;
}
unsigned char digest[CC_MD5_DIGEST_LENGTH];
CC_MD5_Final(digest, &md5);
NSString* s = [NSString stringWithFormat: @"%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x",
digest[0], digest[1],
digest[2], digest[3],
digest[4], digest[5],
digest[6], digest[7],
digest[8], digest[9],
digest[10], digest[11],
digest[12], digest[13],
digest[14], digest[15]];
return s;
}