在IOS中使用swift调用系统相机

2016-01-02

在IOS中使用swift调用系统相机

在IOS的APP开发中,很容易就会遇到使用拍照或录制视频的功能.如果要求并不是太多的话,最简单方式就是调用系统自带的图像获取器UIImagePickerController.

由于UIImagePickerController继承自UINavigationController,所以它的delegate需要实现UIImagePickerControllerDelegate和UINavigationControllerDelegate两个协议.

基本知识

要使用这个类主要要做以下几件事情:

首先要创建一个全局的UIImagePickerController实例.
判断设备是否支持数据来源:
- UIImagePickerController.isSourceTypeAvailable(.Camera)
- UIImagePickerController.isSourceTypeAvailable(.PhotoLibrary)
- UIImagePickerController.isSourceTypeAvailable(.SavedPhotosAlbum)
然后指定数据的来源.一共有三种来源:
- UIImagePickerControllerSourceType.PhotoLibrary 来自系统图库
- UIImagePickerControllerSourceType.Camera 来自相机
- UIImagePickerControllerSourceType.SavedPhotosAlbum 来自相册
如果数据来源是相机,那么还需要设置相机的捕获模式cameraCaptureMode. 主要分为.Photo和.Video
实现各种代理方法接收保存和获取图像的方法.
设置媒体类型,UIImagePickerController根据这个的值来决定选择或拍摄的媒体类型.这个是一个[String] 字符串数组.多个值就表明了可以在拍摄的界面上切换.需要注意的是这个mediaTypes的定义是在MobileCoreService框架下的.当然也可以直接使用String的常量来描述.常用的媒体类型为:

常量名	常量值	说明
kUTTypeImage	public.image	照片
kUTTypeMovie	public.movie	音视频
kUTTypeVideo	public.video	纯视频
kUTTypeAudio	public.audio	纯音频
kUTTypeLivePhoto	com.apple.live-photo	IOS9的动态照片(关于动态图片后面再单独开博文来说)

除了上面说的几个设置外,在使用UIImagePickerController过程中可能还用得到的设置主要有:

modalTransitionStyle: 取景框出现效果
allowsEditing: 是否允许编辑,只有在showsCameraControls属性为true时才有效
showsCameraControls: 是否显示拍照时的工具栏,如果要自定义拍摄界面,需要把这个工具栏隐藏掉
videoMaximumDuration: 录制视频的时长, 默认是10秒
videoQuality: 视频质量,枚举定义在UIImagePickerControllerQualityType中
cameraDevice: 前置,还是后置摄像头,枚举定义在UIImagePickerControllerCameraDevice
cameraFlashMode:闪光灯模式,枚举定义在UIImagePickerControllerCameraFlashMode

有了这些准备,就可以开始来实现一个最简单的DEMO了.

Demo

DEMO很简单,在一个APP上增加一个按钮,点击这个按钮,打开系统自带的摄像头.然后可以进行拍摄,最后把拍摄结果保存到相册中.

首先先创建一个UIImagePickerController:

1	let imagePickerController:UIImagePickerController = UIImagePickerController()

给某个ViewController上增加UIImagePickerControllerDelegate和UINavigationControllerDelegate两个协议.

class ViewController: UIViewController,UIImagePickerControllerDelegate,UINavigationControllerDelegate {
	override func viewDidLoad() {
		imagePickerController.delegate = self
	}
	...
}

然后设置PickerController的初始值:

imagePickerController.modalTransitionStyle = .FlipHorizontal
   imagePickerController.allowsEditing = true	//是否允许编辑
   imagePickerController.sourceType = .Camera	//数据来源为摄像头
    imagePickerController.videoMaximumDuration = 15      //模式录制视频长度,单位秒
    imagePickerController.mediaTypes = ["public.image","public.movie"]        //允许的相机类型(拍照,摄像....)
    imagePickerController.videoQuality = .TypeHigh		     //视频质量
    imagePickerController.cameraCaptureMode = .Photo		//初始摄像头的模式

设置界面按钮的事件响应,在相应中增加打开imagePickerController视图的方法:

1 2	self.presentViewController(imagePickerController, animated: true) { () -> Void in }

实现完成照片或视频的拍摄回调代理方法:func imagePickerController(picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : AnyObject]):

func imagePickerController(picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : AnyObject]) {
	  //获取媒体的类型
       let mediaType = info[UIImagePickerControllerMediaType] as! String
       
       //如果媒体是照片
       if mediaType == kUTTypeImage as String {
           //获取到拍摄的照片, UIImagePickerControllerEditedImage是经过剪裁过的照片,UIImagePickerControllerOriginalImage是原始的照片
           let image = info[UIImagePickerControllerEditedImage] as! UIImage
           
           //调用方法保存到图像库中
           UIImageWriteToSavedPhotosAlbum(image, self,"image:didFinishSavingWithError:contextInfo:", nil)
           
       }else {
           //视频
           //获取到视频的临时路径
           let urlStr =  (info[UIImagePickerControllerMediaURL] as! NSURL).path
           //启动异步线程保存视频到图像库中
           dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), { () -> Void in
           //调用方法保存到图像库中
               UISaveVideoAtPathToSavedPhotosAlbum(urlStr!, self, "video:didFinishSavingWithError:contextInfo:", nil)
           })
       }
       
       //关闭照相框
       self.dismissViewControllerAnimated(true, completion: nil)
   }

实现完成保存后的结果回调方法func image(image: UIImage, didFinishSavingWithError error: NSError?, contextInfo:UnsafePointer<Void>):

func image(image: UIImage, didFinishSavingWithError error: NSError?, contextInfo:UnsafePointer<Void>) {
       if error == nil {
           let ac = UIAlertController(title: "Saved!", message: "成功保存照片到图库", preferredStyle: .Alert)
           ac.addAction(UIAlertAction(title: "OK", style: .Default, handler: nil))
           presentViewController(ac, animated: true, completion: nil)
       } else {
           let ac = UIAlertController(title: "Save error", message: error?.localizedDescription, preferredStyle: .Alert)
           ac.addAction(UIAlertAction(title: "OK", style: .Default, handler: nil))
           presentViewController(ac, animated: true, completion: nil)
       }
   }

实现完成保存视频后的结果回调方法func video(videoPath: String, didFinishSavingWithError error: NSError?, contextInfo:UnsafePointer<Void>):

func video(videoPath: String, didFinishSavingWithError error: NSError?, contextInfo:UnsafePointer<Void>) {
       if error == nil {
           let ac = UIAlertController(title: "Saved!", message: "成功保存视频到图库", preferredStyle: .Alert)
           ac.addAction(UIAlertAction(title: "OK", style: .Default, handler: nil))
           presentViewController(ac, animated: true, completion: nil)
       } else {
           let ac = UIAlertController(title: "Save error", message: error?.localizedDescription, preferredStyle: .Alert)
           ac.addAction(UIAlertAction(title: "OK", style: .Default, handler: nil))
           presentViewController(ac, animated: true, completion: nil)
       }
   }

这样就完成了打开系统相机,并把拍摄的结果放入系统默认的相薄中的全部功能了.

自定义相薄

到目前为止照片等都是保存到系统默认的相机胶卷这个相薄中. 但是像QQ 微信这些应用都是可以把图片存放到自己的相薄中的.这就要求程序中对相薄进行操作了.

在IOS9中,要操作相薄的话,需要引入import Photos库.然后使用PHPhotoLibrary这个类.

先说创建相薄:

首先需要定义一个PHAssetCollection对象:

1	private var assetCollection:PHAssetCollection?

新增一个创建相薄的方法createAlbum:

func createAlbum() {
	 //创建一个FetchOptions,属性选择器
       let fetchOptions = PHFetchOptions()
       //指定相薄的名称
       fetchOptions.predicate = NSPredicate(format: "title = %@", "测试用")
       //获取相薄的对象
       let collection = PHAssetCollection.fetchAssetCollectionsWithType(.Album, subtype: .Any, options: fetchOptions)
       
       //如果查询出的第一个对象存在,那么就说明相薄已经存在了,直接赋值
       if let _ = collection.firstObject {
           assetCollection =  collection.firstObject as? PHAssetCollection
       }else {
       	  //否则需要创建一个新的相薄
           var assetCollectionPlaceholder:PHObjectPlaceholder!
           //调用performChanges方法来创建相薄
           PHPhotoLibrary.sharedPhotoLibrary().performChanges({ () -> Void in
               //根据title来创建一个相薄的请求
               let createAlbumRequest = PHAssetCollectionChangeRequest.creationRequestForAssetCollectionWithTitle("测试用")
               //获取出请求中的placeholder
               assetCollectionPlaceholder = createAlbumRequest.placeholderForCreatedAssetCollection
               }) { (success, error) -> Void in
                   //创建完成的回调
                   if (!success) {
                       NSLog("Error creating album: \(error)");
                   }else{
                   	//如果创建成功.那么就要获取到PHAssetCollection,只有有了这个才能把照片存放到这个相薄中
                       let collectionFetchResult = PHAssetCollection.fetchAssetCollectionsWithLocalIdentifiers([assetCollectionPlaceholder.localIdentifier], options: nil)
                       self.assetCollection =  collectionFetchResult.firstObject as? PHAssetCollection
                   }
           }
       }
   }

创建完成相薄后,就可以保存照片到相薄中了:

func imagePickerController(picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : AnyObject]) {
       let mediaType = info[UIImagePickerControllerMediaType] as! String
       
       //尝试创建相薄
       createAlbum()
       
       if mediaType == kUTTypeImage as String {
           //图片
           let image = info[UIImagePickerControllerEditedImage] as! UIImage
           //使用线程同步     
                  dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), {
               //保存到自定义的相薄中
               PHPhotoLibrary.sharedPhotoLibrary().performChanges({ () -> Void in
                   //根据相片得到保存的请求
                   let assetRequest = PHAssetChangeRequest.creationRequestForAssetFromImage(image)
                   //找到placehodler
                   let assetPlaceholder = assetRequest.placeholderForCreatedAsset
                   //创建photosAsset
                   let photosAsset = PHAsset.fetchAssetsInAssetCollection(self.assetCollection!, options: nil)
                   //实例化 保存事件
                   if let albumChangeRequest = PHAssetCollectionChangeRequest(forAssetCollection: self.assetCollection!, assets: photosAsset) {
                   	//执行相薄照片的保存
                       albumChangeRequest.addAssets([assetPlaceholder!])
                   }
                   
                   }, completionHandler: { (success, error) -> Void in
                       dispatch_async(dispatch_get_main_queue(), {
                           NSLog("Adding Image to Library -> %@", (success ? "Sucess":"Error!"))
                           //
                           if !success {
                               //表示没有保存成功,尝试保存到系统自带的里面
                               //保存到图库
                               UIImageWriteToSavedPhotosAlbum(image, self,"image:didFinishSavingWithError:contextInfo:", nil)
                           }
                           //保存陈红
                           self.dismissViewControllerAnimated(true, completion: nil)
                       })
               })
           })
           
       }else {
           //视频
           ...
       }
   }

如此就能保存相片到自定义的相薄中了,其实对相薄还可以有其他的操作,比如列出所有相薄的名字,删除相薄等等.这个具体的参考PHPhotoLibrary类即可.

总结

本文简单的介绍了一下,如何调用系统自带的相机和相册来进行照片和视频的拍摄.同时也介绍了如何自定义相薄,为以后更高级的拍摄功能做了准备.