iOS图片压缩

提到从摄像头/相册获取图片是面向终端用户的，由用户去浏览并选择图片为程序使用。在这里，我们需要过UIImagePickerController类来和用户交互。
使用UIImagePickerController和用户交互，我们需要实现2个协议。
View Code
代码如下 复制代码

pragma mark 从用户相册获取活动图片

- (void)pickImageFromAlbum
{ imagePicker = [[UIImagePickerController alloc] init]; imagePicker.delegate =self; imagePicker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary; imagePicker.modalTransitionStyle = UIModalTransitionStyleCoverVertical; imagePicker.allowsEditing =YES;
[self presentModalViewController:imagePicker animated:YES];

}
我们来看看上面的从相册获取图片，我们首先要实例化UIImagePickerController对象，然后设置imagePicker对象为当前对象，设置imagePicker的图片来源为UIImagePickerControllerSourceTypePhotoLibrary，表明当前图片的来源为相册，除此之外还可以设置用户对图片是否可编辑。
View Code
代码如下 复制代码

pragma mark 从摄像头获取活动图片

- (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;//自定义照片样式
  [self presentViewController:pickerImage animated:YES completion:nil];
  }
  以上是从摄像头获取图片，和从相册获取图片只是图片来源的设置不一样，摄像头图片的来源为UIImagePickerControllerSourceTypeCamera。
  　　　　在和用户交互之后，用户选择好图片后，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.TakePhotoBtn setImage:m_selectImage forState:UIControlStateNormal];
  [picker dismissModalViewControllerAnimated:YES];
  return ;
  }
  [picker release];
  }
  //对图片尺寸进行压缩--
  -(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;
  }
  图片保存到本地document里面--以及图片格式的转换
  IOS开发之保存图片到Documents目录及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];
    [ipc dismissModalViewControllerAnimated:YES];
  

  } else {
  NSLog(@"MEdia");
  }

上面的代码是当从相册里面选取图片之后保存到本地程序沙盒，在上面我们得到的图片中不能够得到图片名字，
以及不清楚图片格式，所以这个时候我们需要将其转换成NSdata二进制存储，
image = [info objectForKey:@"UIImagePickerControllerOriginalImage"];
NSData *data;
if (UIImagePNGRepresentation(image) == nil) {
data = UIImageJPEGRepresentation(image, 1);
} else {
data = UIImagePNGRepresentation(image);
}
UIImagePNGRepresentation转换PNG格式的图片为二进制，如果图片的格式为JPEG则返回nil；
[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
我们也可以写成下面的格式存储图片
NSString *pngImage = [filePath stringByAppendingPathComponent:@"Documents/image.png"];
NSString *jpgImage = [filePath stringByAppendingPathComponent:@"Documents/image.jpg"];
[data writeToFile:pngImage atomically:YES];
[data writeToFile:jpgImage atomically:YES];提到从摄像头/相册获取图片是面向终端用户的，由用户去浏览并选择图片为程序使用。在这里，我们需要过UIImagePickerController类来和用户交互。
使用UIImagePickerController和用户交互，我们需要实现2个协议。
View Code
代码如下 复制代码

pragma mark 从用户相册获取活动图片

• (void)pickImageFromAlbum
  {
  imagePicker = [[UIImagePickerController alloc] init];
  imagePicker.delegate =self;
  imagePicker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
  imagePicker.modalTransitionStyle = UIModalTransitionStyleCoverVertical;
  imagePicker.allowsEditing =YES;

  [self presentModalViewController:imagePicker animated:YES];
  }
  我们来看看上面的从相册获取图片，我们首先要实例化UIImagePickerController对象，然后设置imagePicker对象为当前对象，设置imagePicker的图片来源为UIImagePickerControllerSourceTypePhotoLibrary，表明当前图片的来源为相册，除此之外还可以设置用户对图片是否可编辑。
  View Code
  代码如下 复制代码

pragma mark 从摄像头获取活动图片

• (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;//自定义照片样式
  [self presentViewController:pickerImage animated:YES completion:nil];
  }
  以上是从摄像头获取图片，和从相册获取图片只是图片来源的设置不一样，摄像头图片的来源为UIImagePickerControllerSourceTypeCamera。
  　　　　在和用户交互之后，用户选择好图片后，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.TakePhotoBtn setImage:m_selectImage forState:UIControlStateNormal];
  [picker dismissModalViewControllerAnimated:YES];
  return ;
  }
  [picker release];
  }
  //对图片尺寸进行压缩--
  -(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;
  }
  图片保存到本地document里面--以及图片格式的转换
  IOS开发之保存图片到Documents目录及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];
    [ipc dismissModalViewControllerAnimated:YES];
  

  } else {
  NSLog(@"MEdia");
  }

上面的代码是当从相册里面选取图片之后保存到本地程序沙盒，在上面我们得到的图片中不能够得到图片名字，
以及不清楚图片格式，所以这个时候我们需要将其转换成NSdata二进制存储，
image = [info objectForKey:@"UIImagePickerControllerOriginalImage"];
NSData *data;
if (UIImagePNGRepresentation(image) == nil) {
data = UIImageJPEGRepresentation(image, 1);
} else {
data = UIImagePNGRepresentation(image);
}
UIImagePNGRepresentation转换PNG格式的图片为二进制，如果图片的格式为JPEG则返回nil；
[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
我们也可以写成下面的格式存储图片
NSString *pngImage = [filePath stringByAppendingPathComponent:@"Documents/image.png"];
NSString *jpgImage = [filePath stringByAppendingPathComponent:@"Documents/image.jpg"];
[data writeToFile:pngImage atomically:YES];
[data writeToFile:jpgImage atomically:YES];