.m文件

#import <Foundation/Foundation.h>

@interface MD5 : NSObject

+ (NSString *)MD5:(NSString *)mdStr;

@end

.h文件

#import "MD5.h"
#import "CommonCrypto/CommonDigest.h"

@implementation MD5

/**
 * MD5加密
 *
 * return  加密后的字符串
 */
+ (NSString *)MD5:(NSString *)mdStr {
    const char *original_str = [mdStr UTF8String];
    unsigned char result[CC_MD5_DIGEST_LENGTH];
    CC_MD5(original_str, strlen(original_str), result);
    NSMutableString *hash = [NSMutableString string];
    for (int i = 0; i < CC_MD5_DIGEST_LENGTH; i++)
        [hash appendFormat:@"%02X", result[i]];
    return [hash lowercaseString];
}

@end