引入OC类库

md5.h:

#import <UIKit/UIKit.h>

@interface Md5Controller : UIViewController

@end

md5.m:

#import "Md5Controller.h"

@interface Md5Controller ()

@end

@implementation Md5Controller

- (void)viewDidLoad {

    [super viewDidLoad];

    // Do any additional setup after loading the view.

}

- (void)didReceiveMemoryWarning {

    [super didReceiveMemoryWarning];

    // Dispose of any resources that can be recreated.

}

/*

#pragma mark - Navigation

// In a storyboard-based application, you will often want to do a little preparation before navigation

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {

    // Get the new view controller using [segue destinationViewController].

    // Pass the selected object to the new view controller.

}

*/

@end

桥接文件：

#import <CommonCrypto/CommonCrypto.h>

可以直接加在文件里面：

extension String {

    func md5() -> String! {

        let str = self.cStringUsingEncoding(NSUTF8StringEncoding)

        let strLen = CUnsignedInt(self.lengthOfBytesUsingEncoding(NSUTF8StringEncoding))

        let digestLen = Int(CC_MD5_DIGEST_LENGTH)

        let result = UnsafeMutablePointer<CUnsignedChar>.alloc(digestLen)

        CC_MD5(str!, strLen, result)

        var hash = NSMutableString()

        for i in 0..<digestLen {

            hash.appendFormat("%02x", result[i])

        }

        result.destroy()

        return String(format: hash)

    }

}

打印测试：

        println("hello".md5())