从摄像头或者是从相冊中读取图片。须要通过UIImagePickerController类来实现，在使用UIImagePickerController时，须要是实现以下两个协议

<UINavigationControllerDelegate,UIImagePickerControllerDelegate>

1、从相冊中读取图片

首先要实例化UIImagePickerController对象imagePicker。设置imagePicker的图片来源为UIImagePickerControllerSourceTypePhotoLibrary，表明当前图片的来源为用户的相冊。

以及设置图片是否可被编辑allowsEditing。

#pragma mark - 从用户相冊获取图片

- (void)pickImageFromAlbum

{

    imagePicker = [[UIImagePickerController alloc] init];

    imagePicker.delegate =self;

    imagePicker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;

    imagePicker.modalTransitionStyle = UIModalTransitionStyleCoverVertical;

    imagePicker.allowsEditing =YES;

    [self presentModalViewController:imagePicker animated:YES];

}

2、从相冊中读取图片

#pragma mark - 从摄像头获取图片

- (void)pickImageFromCamera

{

    imagePicker = [[UIImagePickerController alloc] init];

    imagePicker.delegate =self;

    imagePicker.sourceType = UIImagePickerControllerSourceTypeCamera;

    imagePicker.modalTransitionStyle = UIModalTransitionStyleCoverVertical;

    imagePicker.allowsEditing =YES;

    [self presentModalViewController:imagePicker animated:YES];

}

//打开相机

- (IBAction)touch_photo:(id)sender {

    // for iphone

    UIImagePickerController *pickerImage = [[UIImagePickerController alloc] init];

   if([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) {

        pickerImage.sourceType = UIImagePickerControllerSourceTypeCamera;

        pickerImage.mediaTypes = [UIImagePickerController availableMediaTypesForSourceType:pickerImage.sourceType];

    }

    pickerImage.delegate =self;

    pickerImage.allowsEditing =YES;//自己定义照片样式

    [self presentViewController:pickerImage animated:YES completion:nil];

}

在用户现则好图片后。会回调选择结束的方法

-(void)imagePickerController:(UIImagePickerController*)picker didFinishPickingMediaWithInfo:(NSDictionary*)info

{

    //初始化imageNew为从相机中获得的--

    UIImage *imageNew = [info objectForKey:@"UIImagePickerControllerOriginalImage"];

    //设置image的尺寸

    CGSize imagesize = imageNew.size;

    imageSize.height =626;

    imageSize.width =413;

    //对图片大小进行压缩--

    imageNew = [self imageWithImage:imageNew scaledToSize:imageSize];

    NSData *imageData = UIImageJPEGRepresentation(imageNew,0.00001);

   if(m_selectImage==nil)

    {

        m_selectImage = [UIImage imageWithData:imageData];

        NSLog(@"m_selectImage:%@",m_selectImage);

        [self.takePhotoButton setImage:m_selectImage forState:UIControlStateNormal];

        [picker dismissModalViewControllerAnimated:YES];

       return ;

    }

}

对图片进行压缩

-(UIImage*)imageWithImage:(UIImage*)image scaledToSize:(CGSize)newSize

{

    // Create a graphics image context

    UIGraphicsBeginImageContext(newSize);

    // Tell the old image to draw in this new context, with the desired

    // new size

    [image drawInRect:CGRectMake(0,0,newSize.width,newSize.height)];

    // Get the new image from the context

    UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext();

    // End the context

    UIGraphicsEndImageContext();

    // Return the new image.

   return newImage;

}

将图片保存到Documents文件夹及PNG、JPEG格式相互转换

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary*)info {

    NSString *mediaType = [info objectForKey:UIImagePickerControllerMediaType];

    if ([mediaType isEqualToString:@"public.image"]){

        image = [info objectForKey:@"UIImagePickerControllerOriginalImage"];

        NSData *data;

        if (UIImagePNGRepresentation(image) == nil) {

            data = UIImageJPEGRepresentation(image, 1);

        } else {

            data = UIImagePNGRepresentation(image);

        }

        NSFileManager *fileManager = [NSFileManager defaultManager];

        NSString *filePath = [NSString stringWithString:[self getPath:@"image1"]];         //将图片存储到本地documents

         [fileManager createDirectoryAtPath:filePath withIntermediateDirectories:YES attributes:nil error:nil];

         [fileManager createFileAtPath:[filePath stringByAppendingString:@"/image.png"] contents:dataAttributes:nil];

        UIImage *editedImage = [[UIImage alloc] init];

        editedImage = image;

        CGRect rect = CGRectMake(0, 0, 64, 96);

        UIGraphicsBeginImageContext(rect.size);

        [editedImage drawInRect:rect];

        editedImage = UIGraphicsGetImageFromCurrentImageContext();

        UIButton *imageButton = [UIButton buttonWithType:UIButtonTypeCustom];

        imageButton.frame = CGRectMake(10, 10, 64, 96);

        [imageButton setImage:editedImage forState:UIControlStateNormal];

        [self.view addSubview:imageButton];

        [imageButton addTarget:self action:@selector(imageAction:)forControlEvents:UIControlEventTouchUpInside];

        [self dismissModalViewControllerAnimated:YES];

    } else {

        NSLog(@"Media");

    }

在上面的方法中不能得到图片的名称及格式。所以须要将其转换成NSData二进制存储

 image = [info objectForKey:@"UIImagePickerControllerOriginalImage"];

NSData *data;

        if (UIImagePNGRepresentation(image) == nil) {

            data = UIImageJPEGRepresentation(image, 1);

        } else {

            data = UIImagePNGRepresentation(image);

        }

[fileManager createFileAtPath:[filePath stringByAppendingString:@"/image.png"] contents:data attributes:nil];  //将图片保存为PNG格式

 [fileManager createFileAtPath:[filePath stringByAppendingString:@"/image.jpg"] contents:data attributes:nil]; //将图片保存为JPEG格式

【參考资料：http://www.open-open.com/】