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ios基础篇(一)—— UIImagePickerController类

程序员文章站 2024-01-15 15:34:28
UIImagePickerController简述:UIImagePickerController 类是获取选择图片和视频的用户接口,我们可以用UIImagePickerController选择我们所需要的图片和视频。注:UIImagePickerController不能够任意定制,也不可以继承生成子类。一、UIImagePickerController的属性:1、sourceType设置UIImagePicker照片源类型,默认有3种。照片源类型指定使用模式(照相机/相册/照片库)...

UIImagePickerController简述:

UIImagePickerController 类是获取选择图片和视频的用户接口,我们可以用UIImagePickerController选择我们所需要的图片和视频。

注:UIImagePickerController不能够任意定制,也不可以继承生成子类。

一、UIImagePickerController的属性:

1、sourceType

设置UIImagePicker照片源类型,默认有3种。照片源类型

指定使用模式(照相机/相册/照片库)

enum {
UIImagePickerControllerSourceTypePhotoLibrary,  //照片库(通过同步存放的,用户不能删除)
UIImagePickerControllerSourceTypeCamera,  //照相机
UIImagePickerControllerSourceTypeSavedPhotosAlbum //保存的照片(通过拍照或者截屏保存的,用户可以删除)
};

2、BOOL showsCameraControls

设置拍照时的下方的工具栏是否显示,如果需要自定义拍摄界面,则可把该工具栏隐藏。

3. videoMaximumDuration

设置UIImagePicker的最大视频持续时间.默认10分钟

4. + availableMediaTypesForSourceType: // 指定源可用的媒体种类

 //获得相机模式下支持的媒体类型

NSArray* availableMediaTypes =
[UIImagePickerController availableMediaTypesForSourceType:UIImagePickerControllerSourceTypeCamera];

3、BOOL allowsEditing

设置当拍照完或在相册选完照片后,是否跳到编辑模式进行图片剪裁即是否允许编辑

showsCameraControls=Yes时才有效果。

[imagePicker setAllowsEditing:YES]; 

4、cameraDevice

使用的镜头(默认后置的)

判断设备是否支持前置摄像头/后置摄像头

enum {
     UIImagePickerControllerCameraDeviceRear,
     UIImagePickerControllerCameraDeviceFront
     };

+ isCameraDeviceAvailable: // 摄像设备是否可用.
+ availableCaptureModesForCameraDevice: // 设备可用的选取模式 

  cameraCaptureMode //相机捕获模式

5、cameraFlashMode

设置闪光灯模式  (默认自动)

 enum {
     UIImagePickerControllerCameraFlashModeOff  = -1,
     UIImagePickerControllerCameraFlashModeAuto = 0,
     UIImagePickerControllerCameraFlashModeOn   = 1
     };
 + isFlashAvailableForCameraDevice: // 是否有闪光能力

6、mediaTypes

设置相机支持的类型,拍照和录像

+ (NSArray *)availableMediaTypesForSourceType:(UIImagePickerControllerSourceType)sourceType
  • UIImageWriteToSavedPhotosAlbum保存图像,
  • UISaveVideoAtPathToSavedPhotosAlbum保存视频.
  • 4.0后使用writeImageToSavedPhotosAlbum:metadata:completionBlock:保存元数据.

一共有三个可选的代理方法UIImagePickerControllerDelegate 

– imagePickerController:didFinishPickingMediaWithInfo:  
– imagePickerControllerDidCancel:  
– imagePickerController:didFinishPickingImage:editingInfo: 
- (void)imagePickerController:(UIImagePickerController *)picker 
didFinishPickingMediaWithInfo:(NSDictionary *)info

info中包括选取的照片,视频的主要信息

NSString *const UIImagePickerControllerMediaType;       选取的类型 public.image  public.movie
NSString *const UIImagePickerControllerOriginalImage;    修改前的UIImage object.
NSString *const UIImagePickerControllerEditedImage;    修改后的UIImage object.
NSString *const UIImagePickerControllerCropRect;原始图片的尺寸NSValue object containing a CGRect data type
NSString *const UIImagePickerControllerMediaURL;     视频在文件系统中 的 NSURL地址

7、cameraViewTransform

设置拍摄时屏幕的view的transform属性,可以实现旋转,缩放功能

enum{

CGAffineTransformMakeRotation;

CGAffineTransformMakeScale;

}

二、UIImagePickerController回调方法:

1、成功获得相片或视频后的回调

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

 - (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info{
    //通过UIImagePickerControllerMediaType判断返回的是照片还是视频
      NSString* type = [info objectForKey:UIImagePickerControllerMediaType];
      //如果返回的type等于kUTTypeImage,代表返回的是照片,并且需要判断当前相机使用的sourcetype是拍照还是相册
      if ([type isEqualToString:(NSString*)kUTTypeImage]&&picker.sourceType==UIImagePickerControllerSourceTypeCamera) {
          //获取照片的原图
          UIImage* original = [info
  objectForKey:UIImagePickerControllerOriginalImage];
          //获取图片裁剪的图
         UIImage* edit = [info objectForKey:UIImagePickerControllerEditedImage];
         //获取图片裁剪后,剩下的图
         UIImage* crop = [info objectForKey:UIImagePickerControllerCropRect];
         //获取图片的url
         NSURL* url = [info objectForKey:UIImagePickerControllerMediaURL];
        //获取图片的metaData数据信息
         NSDictionary* metaData = [info objectForKey:UIImagePickerControllerMediaMetadata];
         //如果是拍照的照片,则需要手动保存到本地,系统不会自动保存拍照成功后的照片
         UIImageWriteToSavedPhotosAlbum(edit, self, @selector(image:didFinishSavingWithError:contextInfo:), nil);
     }else{
     
     }
     //模态方式退出uiimagepickercontroller
     [imagepicker dismissModalViewControllerAnimated:YES];
 }

2、取消照相机的回调

- (void)imagePickerControllerDidCancel:(UIImagePickerController *)picker;

 - (void)imagePickerControllerDidCancel:(UIImagePickerController *)picker{
     //模态方式退出UIImagePickerController
    [imagePicker dismissModalViewControllerAnimated:YES];
}

UIImagePickerController小例子

UIImagePickerController的代理需要遵守这两个协议.<UIImagePickerControllerDelegate, UINavigationControllerDelegate>

#pragma mark 选择照片

- (void)selectPhoto{

    // 1. 首先判断照片源是否可用
    if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypePhotoLibrary]) {
        // 0)实例化控制器
        UIImagePickerController *picker = [[UIImagePickerController alloc]init];
        // 1)设置照片源
        [picker setSourceType:UIImagePickerControllerSourceTypePhotoLibrary];
        // 2) 设置允许修改
        [picker setAllowsEditing:YES];
        // 3) 设置代理
        [picker setDelegate:self];
        // 4) 显示控制器
        [self presentViewController:picker animated:YES completion:nil];

    } else {
        NSLog(@"照片源不可用");
    }
}

#pragma mark - imagePicker代理方法

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info{
    UIImage *image = info[@"UIImagePickerControllerEditedImage"];
    [_imageButton setImage:image forState:UIControlStateNormal];    
    // 关闭照片选择器
    [self dismissViewControllerAnimated:YES completion:nil];    
    // 需要将照片保存至应用程序沙箱,由于涉及到数据存储,同时与界面无关
    // 可以使用多线程来保存图像
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{     
        // 保存图像
        // 1. 取图像路径
        NSArray *docs = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
        NSString *imagePath = [docs[0]stringByAppendingPathComponent:@"abc.png"];
       // 2. 转换成NSData保存
        NSData *imageData = UIImagePNGRepresentation(image);
        [imageData writeToFile:imagePath atomically:YES];
    });
}

UIImagePicker使用步骤:

  1.     检查指定源是否可用. isSourceTypeAvailable:方法.
  2.     检查可用媒体(视频还是只能是图片) availableMediaTypesForSourceType:方法.
  3.     设置界面媒体属性mediaTypes property.
  4.     显示界面使用presentViewController:animated:completion:方法.iPad中是popover形式.需要确保sourceType有效.
  5.     相关操作,移除视图.


如果想创建一个完全自定义界面的image picker来浏览图片,使用 Assets Library Framework Reference中的类. (AV Foundation Programming Guide 中的 “Media Capture and Access to Camera” )

参考:https://www.jianshu.com/p/966a3b9a72be

本文地址:https://blog.csdn.net/qq_41431406/article/details/108975285

相关标签: ios小白