//创建一个相册控制器     UIImagePickerController *pc = [[UIImagePickerController alloc] init];     //图片来源 //    UIImagePickerControllerSourceTypePhotoLibrary  //相册库 //    UIImagePickerControllerSourceTypeCamera      //相机 (模拟器使用相机会崩溃,真机可以) //    UIImagePickerControllerSourceTypeSavedPhotosAlbum 照片库     pc.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;     //是否允许编辑图片     pc.allowsEditing = YES;     pc.delegate = self;  //设置代理  
    
       //相册控制器要遵守两个协议     //把相册控制器 present 出来     [self presentViewController:pc animated:YES completion:nil]; 相册代理里面可以设置 #pragma mark - 相册控制器的代理方法 //选择图片完成后调用 - (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {
      NSLog(@"%@",info);  //得到字典     //保存编辑后的图片 ,在字典里面有信息     self.imageView.image = info[@"UIImagePickerControllerEditedImage"]; //    data 转成image     //UIImage imageWithData:<#(NSData *)#> //    image(.PNG) 转成data     //UIImagePNGRepresentation(<#UIImage *image#>) //    .jpg 转成data     //参数2. 压缩系数,0 - 1.0     NSData *dataOriginal = UIImageJPEGRepresentation(self.imageView.image, 1.0);     NSData *dataEdited = UIImageJPEGRepresentation(self.imageView.image, 0.3);     NSLog(@"%@",NSHomeDirectory());     //把原始的图片保存到沙盒     [dataOriginal writeToFile:[NSString stringWithFormat:@"%@/Library/1.jpg",NSHomeDirectory()] atomically:YES];     //把编辑过的图片也保存进去 方便对比 (编辑了会压缩,压缩过后的图片所占外存更小,放大会模糊)     [dataEdited writeToFile:[NSString stringWithFormat:@"%@/Library/2.jpg",NSHomeDirectory()] atomically:YES];     //返回     [picker dismissViewControllerAnimated:YES completion:nil]; }