//类方法  图片 转换为二进制
+(NSData *)Image_TransForm_Data:(UIImage *)image
{
    NSData *imageData = UIImageJPEGRepresentation(image , 0.5);
    //几乎是按0.5图片大小就降到原来的一半 比如这里 24KB 降到11KB
    return imageData;
}
//调用方法举例
-(void)viewWillAppear:(BOOL)animated
{
    [self Read_ImageData];
}
- (void)viewDidLoad
{
     nav_View=[[NavView alloc]init];
    [self.view addSubview: [nav_View NavView_Title:@"通告"]];
    [super viewDidLoad];
    [self Read_ImageData];
}
//以下方法 就是把一图片压缩成二进制 再转换成图片做显示 效果 不错
-(void)Read_ImageData
{
    UIImageView *imageView1=[[UIImageView alloc]initWithFrame:CGRectMake(0, 80, 200, 200)];
    imageView1.image=[UIImage imageNamed:@"cat_food.png"];
    [self.view addSubview:imageView1]; 
    
    UIImageView *imageView3=[[UIImageView alloc]initWithFrame:CGRectMake(0, 280, 200, 200)];
    imageView3.image=[UIImage imageWithData:[Function Image_TransForm_Data:imageView1.image] ];
    [self.view addSubview:imageView3];
    NSData *data = [NSData dataWithData:[Function Image_TransForm_Data:imageView1.image ]];
    [data writeToFile:[Function CreateTheFolder_From:Library_Cache FileHolderName:MyFolder FileName:@"pp111111.png"] atomically:YES];
}