iOS图片上传及压缩

Posted 2020-07-26 李洪强

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<UIImagePickerControllerDelegate,UINavigationControllerDelegate>。

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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。

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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:YEScompletion: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];