目前，将视频捕获集成到你的应用中的最简单的方法是使用 UIImagePickerController。这是一个封装了完整视频捕获管线和相机 UI 的 view controller。用UIImagePickerController可以自定义系统提供的界面来拍摄并保存视频和照片。
Source type : 这个参数是用来确定是调用摄像头还是调用图片库.UIImagePickerControllerSourceTypeCamera : 提供调用摄像头的界面来拍摄照片视频。UIImagePickerControllerSourceTypePhotoLibrary 调用图片库作为UIImagePickerController数据源。UIImagePickerControllerSourceTypeSavedPhotosAlbum iOS设备中的胶卷相机的图片.作为UIImagePickerController数据源
Mediatypes: NSArray数组。拍摄时：这个属性决定UIImagePickerController界面模式是拍照还是录像.查看已保存多媒体数据，可决定展示的是照片还是视频。kUTTypeImage 表示静态图片, kUTTypeMovie表示录像.把空数组传给这个属性会报异常。在设置此属性前，需要用availableMediaTypesForSourceType:类方法判断这种多媒体类型是否被支持。
Editing controls : 用来指定是否可编辑.将allowsEditing 属性设置为YES表示可编辑,NO表示不可编辑.
delegateid <UINavigationControllerDelegate, UIImagePickerControllerDelegate> delegate: 使用 UIImagePickerController，必须提供遵守UIImagePickerControllerDelegate和UINavigationControllerDelegate协议 的delegate对象.UIImagePickerControllerDelegate提供了两个方法来在照相完成后，与UIImagePickerController对象界面进行交互。imagePickerController:didFinishPickingMediaWithInfo: delegate使用拍摄的照片或者视频的处理逻辑.imagePickerControllerDidCancel(_:) 取消picker view。
1.首先要检查设备是否支持相机录制, 否则设备不支持相机时，会crash 。
if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera] == NO) return; UIImagePickerController *camera = [[UIImagePickerController alloc] init]; camera.sourceType = UIImagePickerControllerSourceTypeCamera;2.检查在 source type中支持的多媒体类型,并设置mediatypes
camera.mediaTypes = [UIImagePickerController availableMediaTypesForSourceType:UIImagePickerControllerSourceTypeCamera];如果只想让摄像头只能摄像,而不能拍照,那应该设置mediaTypes cameraUI.mediaTypes = [[NSArray alloc] initWithObjects: (NSString *) kUTTypeMovie , nil]; kUTTypeImage 对应拍照 kUTTypeMovie 对应摄像 这要导入MobileCoreServices.framework,然后再#import <MobileCoreServices/UTCoreTypes.h>
3.设置delegate，定义拍摄完成后的交互事件处理
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary<NSString *,id> *)info { NSString *mediaType = [info objectForKey: UIImagePickerControllerMediaType]; UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"选择视频" message:nil delegate:self cancelButtonTitle:@"好" otherButtonTitles:nil, nil]; [alertView show]; NSLog(@"didFinishPickingMediaWithInfo info=%@;type = %@", info, mediaType); } - (void)imagePickerControllerDidCancel:(UIImagePickerController *)picker { NSLog(@"imagePickerControllerDidCancel"); [picker dismissViewControllerAnimated:YES completion:nil]; }ViewController.m
#import <MobileCoreServices/UTCoreTypes.h> #import <MediaPlayer/MediaPlayer.h> #import <AVFoundation/AVFoundation.h> #import "ViewController.h" @interface ViewController () <UINavigationControllerDelegate, UIImagePickerControllerDelegate, UIAlertViewDelegate> @end @implementation ViewController - (void)viewDidLoad { [super viewDidLoad]; // Do any additional setup after loading the view, typically from a nib. UIBarButtonItem *rightItem = [[UIBarButtonItem alloc] initWithTitle:@"拍摄" style:UIBarButtonItemStylePlain target:self action:@selector(startCameraControllerFromViewController:)]; self.navigationItem.rightBarButtonItem = rightItem; } - (void)didReceiveMemoryWarning { [super didReceiveMemoryWarning]; // Dispose of any resources that can be recreated. } - (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary<NSString *,id> *)info { NSString *mediaType = [info objectForKey: UIImagePickerControllerMediaType]; UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"选择视频" message:nil delegate:self cancelButtonTitle:@"好" otherButtonTitles:nil, nil]; [alertView show]; NSLog(@"didFinishPickingMediaWithInfo info=%@;type = %@", info, mediaType); } - (void)imagePickerControllerDidCancel:(UIImagePickerController *)picker { NSLog(@"imagePickerControllerDidCancel"); [picker dismissViewControllerAnimated:YES completion:nil]; } // 设备是否被授权访问相机 -(BOOL)isCameraAuthorized { AVAuthorizationStatus auth = [AVCaptureDevice authorizationStatusForMediaType:AVMediaTypeVideo]; return (auth == AVAuthorizationStatusAuthorized); } // 请访问求相机授权 - (void)requestCameraAuthorization { NSString *title = @"请在\设置-隐私-相机\"选项中，允许访问你的相机。"; AVAuthorizationStatus auth = [AVCaptureDevice authorizationStatusForMediaType:AVMediaTypeVideo]; if (auth == AVAuthorizationStatusNotDetermined) { [AVCaptureDevice requestAccessForMediaType:AVMediaTypeVideo completionHandler:^(BOOL granted) { dispatch_async(dispatch_get_main_queue(), ^{ UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:title message:nil delegate:self cancelButtonTitle:@"好" otherButtonTitles:nil]; [alertView show]; }); }]; } else { UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:title message:nil delegate:self cancelButtonTitle:@"好" otherButtonTitles:nil]; [alertView show]; } } - (void)startCameraControllerFromViewController: (UIViewController*)controller { if (![self isCameraAuthorized]) { [self requestCameraAuthorization]; } if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera] == NO) return; UIImagePickerController *camera = [[UIImagePickerController alloc] init]; camera.sourceType = UIImagePickerControllerSourceTypeCamera; camera.delegate = self; camera.mediaTypes = [UIImagePickerController availableMediaTypesForSourceType:UIImagePickerControllerSourceTypeCamera]; [self presentViewController:camera animated:YES completion:nil]; } @endAppDelegate.m
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions { // Override point for customization after application launch. self.window = [[UIWindow alloc] initWithFrame:[UIScreen mainScreen].bounds]; self.viewController = [[ViewController alloc] init]; self.navigationController = [[UINavigationController alloc] init]; [self.navigationController pushViewController:self.viewController animated:YES]; self.window.rootViewController = self.navigationController; return YES; }横向拍摄视频，完成拍摄后点击“使用视频”，摄像头被打开，背景出现摄像流。
bug.png设备和系统： iPhone6Plus 9.1 ，上述情况 iPhone5s 8.3 , 上述情况 iPhone4s 7.1.1, 上述情况，但是显示是已拍摄视频的最后一帧。
问题原因： 调用系统摄像机录像时,UIImagePickerController视图有两个关键子view，CMKVideoPreviewView和PLAVPlayerView。PLAVPlayerView 用来播放已录制的视频。CMKVideoPreviewView 负责展示摄像头实时拍摄的视频流。 PreviewView在不同系统版本有不同的名字：
9.1系统的类名是CMKVideoPreviewView;8.3系统是CAMVideoPreviewView;7.1系统是 PLVideoPreviewView）视图层次结构：CMKVideoPreviewView在下，PLAVPlayerView 在上。横屏拍摄视频，完成拍摄后，由于UIImagePickerController官方只支持竖屏模式，系统自动转为竖屏模式并更新PLVideoPosterFrameView的UIImageView（已录制视频的快照）的frame为 (0, 212,75, 414, 310,5),所以原本被遮挡的CMKVideoPreviewView就显示出来了。
Paste_Image.png解决方案： 思路：在点击“使用视频”之后，弹出“压缩”toast提示之前，获取CMKVideoPreviewView对象的指针，并讲该对象的hidden属性设为YES.由于CMKVideoPreviewView是private frameworks中的类，无法直接获取对象，但可通过public api : view.subviews ,在子view中递归查找目标对象，安全地获取到该对象。此方法可以通过appstore的审查。 如何安全使用私有库类
- (void)setVideoPreviewHidden:(BOOL)hidden inPicker:(UIImagePickerController *)picker { UIView *view = nil; float systemVersion = UIDevice.currentDevice.systemVersion.floatValue; if (systemVersion>= 10.0) { return; } else if (systemVersion>= 9.0) { view = UIViewFindSubview(picker.view, [NSClassFromString(@"CMKVideoPreviewView") class]); } else if (systemVersion >= 8.0) { view = UIViewFindSubview(picker.view, [NSClassFromString(@"CAMVideoPreviewView") class]); } else if (systemVersion >= 7.0) { view = UIViewFindSubview(picker.view, [NSClassFromString(@"PLVideoPreviewView") class]); } view.hidden = hidden; } NS_INLINE UIView *UIViewFindSubview(UIView *view, Class viewClass) { for (UIView *subview in view.subviews) { if ([subview isKindOfClass:viewClass]) { return subview; } else { UIView *ret = UIViewFindSubview(subview, viewClass); if (ret) return ret; } } return nil; }Taking Pictures and Movies
ios设备上捕获视频
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