参考文章：其中文章的：http://blog.csdn.net/ztp800201/article/details/9470065

下载包

其中 包括GTMBase包下载地址 http://pan.baidu.com/share/link?shareid=928474681&uk=923776187
#import "ViewController.h"

#import "GTMBase64.h"

@interface ViewController (){

}

@end

@implementation ViewController

- (void)viewDidLoad

{

    [super viewDidLoad];

}

#pragma mark -GTMBas4 64编码

- (IBAction)codeclick:(id)sender {

    [self codeImg];

}

- (IBAction)encodeClick:(id)sender {

    [self DecodeImg];

}

#pragma mark -文字编码

-(void)TextCode{

    NSString *str=@"Hello world";

    NSData *Data=[str dataUsingEncoding:NSUTF8StringEncoding];

    //进行编码

    Data =[GTMBase64 encodeData:Data];

    NSString *codestr=[[[NSString alloc] initWithData:Data encoding:NSUTF8StringEncoding] autorelease];

    self.lbMessage.text=codestr;

}

#pragma mark -图片编码

-(void)codeImg{

    NSString *path=[[NSBundle mainBundle] pathForResource:@"school_back" ofType:@"png"];

    UIImage *img= [UIImage imageWithContentsOfFile:path];

    NSData *data=UIImageJPEGRepresentation(img, 1.0);//UIImageJPEGRepresentation返回图片较小，但是清晰度模糊

//    NSData *data=UIImagePNGRepresentation(img);//UIImagePNGRepresentation图片大，清晰

   data= [GTMBase64 encodeData:data];

    NSLog(@"-->%@",[[[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding] autorelease]);

    self.lbMessage.text=[[[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding] autorelease];

}

//==========================

#pragma mark -文字解码

-(void)TextDecode{

    NSString *codeStr=self.lbMessage.text;

    NSData *data=[codeStr dataUsingEncoding:NSUTF8StringEncoding];

    data=  [GTMBase64 decodeData:data];

    self.lbMessage.text=[[[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding] autorelease];

}

#pragma mark -图片解码

-(void)DecodeImg{

    NSString *codestr=self.lbMessage.text;

    NSData *data=[codestr dataUsingEncoding:NSUTF8StringEncoding];

    data=[GTMBase64 decodeData:data];

    UIImage *ima=[UIImage imageWithData:data];

    self.img.image=ima;

}

- (void)dealloc {

    [_lbMessage release];

    [_img release];

    [super dealloc];

}

@end