iOS录制视频遇到的那些坎

先说一下我的视频录制的思路：

1.首先创建一个VC专门用来渲染和显示视频的控制器

2.在viewWillAppear中做好如下初始化准备录音步骤:

#import "RecordVideoViewController.h"
//音视频
#import <AVFoundation/AVFoundation.h>
#import <AssetsLibrary/AssetsLibrary.h>
//文件
#import "FCFileManager.h"
//网络
#import "DRDAPIPostCall.h"
//提示
#import "UIView+Toast.h"

#define RGBA_COLOR(R, G, B, A) [UIColor colorWithRed:((R) / 255.0f) green:((G) / 255.0f) blue:((B) / 255.0f) alpha:A]

typedef void(^PropertyChangeBlock)(AVCaptureDevice *captureDevice);

@interface RecordVideoViewController ()<AVCaptureFileOutputRecordingDelegate>     //视频文件输出代理
@property (strong,nonatomic) AVCaptureSession *captureSession;                    //负责输入和输出设备之间的数据传递
@property (strong,nonatomic) AVCaptureDeviceInput *captureDeviceInput;            //负责从AVCaptureDevice获得输入数据
@property (strong,nonatomic) AVCaptureMovieFileOutput *captureMovieFileOutput;    //视频输出流
@property (strong,nonatomic) AVCaptureVideoPreviewLayer *captureVideoPreviewLayer;//相机拍摄预览图层
@property (assign,nonatomic) BOOL enableRotation;                                //是否允许旋转（注意在视频录制过程中禁止屏幕旋转）
@property (assign,nonatomic) CGRect *lastBounds;                                 //旋转的前大小
@property (assign,nonatomic) UIBackgroundTaskIdentifier backgroundTaskIdentifier;//后台任务标识
@property (weak, nonatomic) IBOutlet UIView *viewContainer;                      //本控制器
@property (weak, nonatomic) IBOutlet UIImageView *focusCursor;                   //聚焦光标
@property (weak, nonatomic) IBOutlet UIProgressView *videoProgress;              //加载进度条
@property (weak, nonatomic) IBOutlet UIButton *recordBtn;                        //录屏按钮
@property (weak, nonatomic) IBOutlet UILabel *recoderTipsLabel;                  //录屏时间显示标签
@property (strong,nonatomic) NSTimer *mTimerForRecord;                           //录屏定时器

@end

@implementation RecordVideoViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view from its nib.
    
    //文字颜色
    [_recoderTipsLabel setTextColor:RGBA_COLOR(32, 192, 227, 1)];
}
- (IBAction)backButtonAction:(id)sender {
    //停止录视频
    [self.captureMovieFileOutput stopRecording];//停止录制
    //关闭监听
    [self removeNotification];
    //关闭定时器
    [_mTimerForRecord invalidate];
    _mTimerForRecord = nil;
    [self dismissViewControllerAnimated:YES completion:nil];
}

-(void)viewWillAppear:(BOOL)animated{
    [super viewWillAppear:animated];
    //初始化会话
    _captureSession=[[AVCaptureSession alloc]init];
    if ([_captureSession canSetSessionPreset:AVCaptureSessionPreset1920x1080]) {//设置分辨率
        _captureSession.sessionPreset=AVCaptureSessionPreset1920x1080;
    }
    //获得输入设备
    AVCaptureDevice *captureDevice=[self getCameraDeviceWithPosition:AVCaptureDevicePositionBack];//取得后置摄像头
    if (!captureDevice) {
        NSLog(@"取得后置摄像头时出现问题.");
        return;
    }
    //添加一个音频输入设备
    AVCaptureDevice *audioCaptureDevice=[[AVCaptureDevice devicesWithMediaType:AVMediaTypeAudio] firstObject];
    
    
    NSError *error=nil;
    //根据输入设备初始化设备输入对象，用于获得输入数据
    _captureDeviceInput=[[AVCaptureDeviceInput alloc]initWithDevice:captureDevice error:&error];
    if (error) {
        NSLog(@"取得设备输入对象时出错，错误原因：%@",error.localizedDescription);
        return;
    }
    AVCaptureDeviceInput *audioCaptureDeviceInput=[[AVCaptureDeviceInput alloc]initWithDevice:audioCaptureDevice error:&error];
    if (error) {
        NSLog(@"取得设备输入对象时出错，错误原因：%@",error.localizedDescription);
        return;
    }
    //初始化设备输出对象，用于获得输出数据
    _captureMovieFileOutput=[[AVCaptureMovieFileOutput alloc]init];
    
    //将设备输入添加到会话中
    if ([_captureSession canAddInput:_captureDeviceInput]) {
        [_captureSession addInput:_captureDeviceInput];
        [_captureSession addInput:audioCaptureDeviceInput];
        AVCaptureConnection *captureConnection=[_captureMovieFileOutput connectionWithMediaType:AVMediaTypeVideo];
        if ([captureConnection isVideoStabilizationSupported ]) {
            captureConnection.preferredVideoStabilizationMode=AVCaptureVideoStabilizationModeAuto;
        }
    }
    
    //将设备输出添加到会话中
    if ([_captureSession canAddOutput:_captureMovieFileOutput]) {
        [_captureSession addOutput:_captureMovieFileOutput];
    }
    
    //创建视频预览层，用于实时展示摄像头状态
    _captureVideoPreviewLayer=[[AVCaptureVideoPreviewLayer alloc]initWithSession:self.captureSession];
    NSLog(@"前:%i",[_captureVideoPreviewLayer connection].videoOrientation);
    //新增加

    
    [_captureVideoPreviewLayer connection].videoOrientation = (AVCaptureVideoOrientation)[[UIApplication sharedApplication] statusBarOrientation];

    NSLog(@"后:%i",[_captureVideoPreviewLayer connection].videoOrientation);
    
    CALayer *layer=self.viewContainer.layer;
    layer.masksToBounds=YES;
    
    _captureVideoPreviewLayer.frame=layer.bounds;
    NSLog(@"%@",NSStringFromCGRect(layer.bounds));
    
    _captureVideoPreviewLayer.videoGravity=AVLayerVideoGravityResizeAspectFill;//填充模式


    //将视频预览层添加到界面中
    //[layer addSublayer:_captureVideoPreviewLayer];
    [layer insertSublayer:_captureVideoPreviewLayer below:self.focusCursor.layer];
    
    _enableRotation=NO;
    [self addNotificationToCaptureDevice:captureDevice];
    [self addGenstureRecognizer];
}

#pragma mark - 计时器
- (void)startTimeLabel
{
    _recoderTipsLabel.text = @"00:00";
    _mTimerForRecord = [NSTimer timerWithTimeInterval:1 target:self selector:@selector(toSetRecFlags) userInfo:nil repeats:YES];                   //定时改变录像标
    [[NSRunLoop currentRunLoop] addTimer:_mTimerForRecord forMode:NSRunLoopCommonModes];
    [_mTimerForRecord setFireDate:[NSDate distantPast]];
}

- (void)stopTimeLabel
{
    [_mTimerForRecord setFireDate:[NSDate distantFuture]];
    [_mTimerForRecord invalidate];
    _mTimerForRecord = nil;
    _recoderTipsLabel.text = @"00:00";
}

- (void)toSetRecFlags
{
    NSInteger value = [[[_recoderTipsLabel.text componentsSeparatedByString:@":"] objectAtIndex:0] integerValue]*60 + [[[_recoderTipsLabel.text componentsSeparatedByString:@":"] objectAtIndex:1] integerValue];
    
    value++;
    NSString *minute;
    NSString *second;
    
    if (value/60 > 9)
    {
        minute = [NSString stringWithFormat:@"%d",value/60];
    }
    else
    {
        minute = [NSString stringWithFormat:@"0%d",value/60];
    }
    
    if (value%60 > 9)
    {
        second = [NSString stringWithFormat:@"%d",value%60];
    }
    else
    {
        second = [NSString stringWithFormat:@"0%d",value%60];
    }
    
    [_recoderTipsLabel setTextColor:RGBA_COLOR(32, 192, 227, 1)];//RGBA(32, 192, 227, 1)//RGBA(201, 201, 201, 1)
    [_recoderTipsLabel setText:[NSString stringWithFormat:@"%@:%@",minute,second]];
}

#pragma mark 上传视频
- (IBAction)uploadVideoAction:(id)sender
{
    _videoProgress.hidden = NO;
    NSString *outputFielPath = [FCFileManager pathForTemporaryDirectoryWithPath:@"user_video.mp4"];
        
    DRDAPIPostCall *apiPost = [[DRDAPIPostCall alloc] init];
    [apiPost setApiCompletionHandler:^(id _Nonnull responseObject, NSError * _Nullable error) {
        if (error) {
            [self.view makeToast:[error description] duration:2.0 position:CSToastPositionCenter];
        }
    }];
    [apiPost setApiRequestConstructingBodyBlock:^(id<DRDMultipartFormData> _Nonnull formData) {
        NSData *videoData = [NSData dataWithContentsOfFile:outputFielPath];
        [formData appendPartWithFileData:videoData
                                    name:@"user_video"
                                fileName:@"user_video"
                                mimeType:@"video/mp4"];
    }];
    [apiPost setApiProgressBlock:^(NSProgress * _Nullable progress) {
        __weak typeof(self) weakSelf = self;
        dispatch_async(dispatch_get_main_queue(), ^{
            weakSelf.videoProgress.progress =  progress.fractionCompleted;
            weakSelf.recoderTipsLabel.text = [NSString stringWithFormat:@"上传进度: %.2f%%", progress.fractionCompleted * 100];
        });

    }];
    [apiPost start];
}

#pragma mark 录屏
-(BOOL)shouldAutorotate{
    return NO;
}

-(void)viewDidAppear:(BOOL)animated{
    [super viewDidAppear:animated];
    [self.captureSession startRunning];
}

-(void)viewDidDisappear:(BOOL)animated{
    [super viewDidDisappear:animated];
    [self.captureSession stopRunning];
}



//屏幕旋转时调整视频预览图层的方向
//-(void)willRotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation duration:(NSTimeInterval)duration{
//    AVCaptureConnection *captureConnection=[self.captureVideoPreviewLayer connection];
//    captureConnection.videoOrientation=(AVCaptureVideoOrientation)toInterfaceOrientation;
//}
//旋转后重新设置大小
//-(void)didRotateFromInterfaceOrientation:(UIInterfaceOrientation)fromInterfaceOrientation{
//    _captureVideoPreviewLayer.frame=self.viewContainer.bounds;
//}

-(void)dealloc{
    [self removeNotification];
}
//切换摄像头
- (IBAction)toggleCapture:(id)sender {
    AVCaptureDevice *currentDevice=[self.captureDeviceInput device];
    AVCaptureDevicePosition currentPosition=[currentDevice position];
    [self removeNotificationFromCaptureDevice:currentDevice];
    
    AVCaptureDevice *toChangeDevice;
    AVCaptureDevicePosition toChangePosition=AVCaptureDevicePositionFront;
    if (currentPosition==AVCaptureDevicePositionUnspecified||currentPosition==AVCaptureDevicePositionFront) {
        toChangePosition=AVCaptureDevicePositionBack;
    }
    toChangeDevice=[self getCameraDeviceWithPosition:toChangePosition];
    [self addNotificationToCaptureDevice:toChangeDevice];
    //获得要调整的设备输入对象
    AVCaptureDeviceInput *toChangeDeviceInput=[[AVCaptureDeviceInput alloc]initWithDevice:toChangeDevice error:nil];
    
    //改变会话的配置前一定要先开启配置，配置完成后提交配置改变
    [self.captureSession beginConfiguration];
    //移除原有输入对象
    [self.captureSession removeInput:self.captureDeviceInput];
    [self.captureSession setSessionPreset:AVCaptureSessionPresetHigh];
    //添加新的输入对象
    BOOL isAdded = [self.captureSession canAddInput:toChangeDeviceInput];
    if (isAdded) {
        [self.captureSession addInput:toChangeDeviceInput];
        self.captureDeviceInput=toChangeDeviceInput;
    }else{
        [self.captureSession addInput:self.captureDeviceInput];
    }

    
    //提交会话配置
    [self.captureSession commitConfiguration];
}
- (IBAction)startVideo:(id)sender {
    //根据设备输出获得连接
    AVCaptureConnection *captureConnection=[self.captureMovieFileOutput connectionWithMediaType:AVMediaTypeVideo];

    //根据连接取得设备输出的数据
    if (![self.captureMovieFileOutput isRecording]) {
        self.enableRotation=NO;
        //开始计时
        [self startTimeLabel];
        //切换UI图标
        [_recordBtn setImage:[UIImage imageNamed:@"RecoderBtn_Selected.png"] forState:UIControlStateNormal];
        //如果支持多任务则则开始多任务
        if ([[UIDevice currentDevice] isMultitaskingSupported]) {
            self.backgroundTaskIdentifier=[[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:nil];
        }
        //预览图层和视频方向保持一致
        captureConnection.videoOrientation=[self.captureVideoPreviewLayer connection].videoOrientation;
        NSLog(@"%i",[self.captureVideoPreviewLayer connection].videoOrientation);

        NSString *outputFielPath=[NSTemporaryDirectory() stringByAppendingString:@"user_video.mp4"];
        if ([FCFileManager existsItemAtPath:outputFielPath]) {
            [FCFileManager removeItemAtPath:outputFielPath];
        }
        NSLog(@"save path is :%@",outputFielPath);
        NSURL *fileUrl=[NSURL fileURLWithPath:outputFielPath];
        [self.captureMovieFileOutput startRecordingToOutputFileURL:fileUrl recordingDelegate:self];
    }
    else{
        [self.captureMovieFileOutput stopRecording];//停止录制
        [_recordBtn setImage:[UIImage imageNamed:@"RecoderBtn_Defalut.png"] forState:UIControlStateNormal];//切换UI图标
        [self stopTimeLabel];//结束计时
    }
}



- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

#pragma mark - 视频输出代理
-(void)captureOutput:(AVCaptureFileOutput *)captureOutput didStartRecordingToOutputFileAtURL:(NSURL *)fileURL fromConnections:(NSArray *)connections{
    NSLog(@"开始录制...");
}
-(void)captureOutput:(AVCaptureFileOutput *)captureOutput didFinishRecordingToOutputFileAtURL:(NSURL *)outputFileURL fromConnections:(NSArray *)connections error:(NSError *)error{
    NSLog(@"视频录制完成.");
    //视频录入完成之后在后台将视频存储到相簿
    self.enableRotation=YES;
    UIBackgroundTaskIdentifier lastBackgroundTaskIdentifier=self.backgroundTaskIdentifier;
    self.backgroundTaskIdentifier=UIBackgroundTaskInvalid;
    ALAssetsLibrary *assetsLibrary=[[ALAssetsLibrary alloc]init];
    [assetsLibrary writeVideoAtPathToSavedPhotosAlbum:outputFileURL completionBlock:^(NSURL *assetURL, NSError *error) {
        if (error) {
            NSLog(@"保存视频到相簿过程中发生错误，错误信息：%@",error.localizedDescription);
        }
        if (lastBackgroundTaskIdentifier!=UIBackgroundTaskInvalid) {
            [[UIApplication sharedApplication] endBackgroundTask:lastBackgroundTaskIdentifier];
        }
        NSLog(@"成功保存视频到相簿.");
    }];
    
}

- (void)captureOutput:(AVCaptureFileOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection
{
    [connection setVideoOrientation:AVCaptureVideoOrientationLandscapeRight];
}

#pragma mark - 通知
/**
 *  给输入设备添加通知
 */
-(void)addNotificationToCaptureDevice:(AVCaptureDevice *)captureDevice{
    //注意添加区域改变捕获通知必须首先设置设备允许捕获
    [self changeDeviceProperty:^(AVCaptureDevice *captureDevice) {
        captureDevice.subjectAreaChangeMonitoringEnabled=YES;
    }];
    NSNotificationCenter *notificationCenter= [NSNotificationCenter defaultCenter];
    //捕获区域发生改变
    [notificationCenter addObserver:self selector:@selector(areaChange:) name:AVCaptureDeviceSubjectAreaDidChangeNotification object:captureDevice];
}
-(void)removeNotificationFromCaptureDevice:(AVCaptureDevice *)captureDevice{
    NSNotificationCenter *notificationCenter= [NSNotificationCenter defaultCenter];
    [notificationCenter removeObserver:self name:AVCaptureDeviceSubjectAreaDidChangeNotification object:captureDevice];
}
/**
 *  移除所有通知
 */
-(void)removeNotification{
    NSNotificationCenter *notificationCenter= [NSNotificationCenter defaultCenter];
    [notificationCenter removeObserver:self];
}

-(void)addNotificationToCaptureSession:(AVCaptureSession *)captureSession{
    NSNotificationCenter *notificationCenter= [NSNotificationCenter defaultCenter];
    //会话出错
    [notificationCenter addObserver:self selector:@selector(sessionRuntimeError:) name:AVCaptureSessionRuntimeErrorNotification object:captureSession];
}

/**
 *  设备连接成功
 *
 *  @param notification 通知对象
 */
-(void)deviceConnected:(NSNotification *)notification{
    NSLog(@"设备已连接...");
}
/**
 *  设备连接断开
 *
 *  @param notification 通知对象
 */
-(void)deviceDisconnected:(NSNotification *)notification{
    NSLog(@"设备已断开.");
}
/**
 *  捕获区域改变
 *
 *  @param notification 通知对象
 */
-(void)areaChange:(NSNotification *)notification{
    NSLog(@"捕获区域改变...");
}

/**
 *  会话出错
 *
 *  @param notification 通知对象
 */
-(void)sessionRuntimeError:(NSNotification *)notification{
    NSLog(@"会话发生错误.");
}

#pragma mark - 私有方法

/**
 *  取得指定位置的摄像头
 *
 *  @param position 摄像头位置
 *
 *  @return 摄像头设备
 */
-(AVCaptureDevice *)getCameraDeviceWithPosition:(AVCaptureDevicePosition )position{
    NSArray *cameras= [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
    for (AVCaptureDevice *camera in cameras) {
        if ([camera position]==position) {
            return camera;
        }
    }
    return nil;
}

/**
 *  改变设备属性的统一操作方法
 *
 *  @param propertyChange 属性改变操作
 */
-(void)changeDeviceProperty:(PropertyChangeBlock)propertyChange{
    AVCaptureDevice *captureDevice= [self.captureDeviceInput device];
    NSError *error;
    //注意改变设备属性前一定要首先调用lockForConfiguration:调用完之后使用unlockForConfiguration方法解锁
    if ([captureDevice lockForConfiguration:&error]) {
        propertyChange(captureDevice);
        [captureDevice unlockForConfiguration];
    }else{
        NSLog(@"设置设备属性过程发生错误，错误信息：%@",error.localizedDescription);
    }
}

/**
 *  设置闪光灯模式
 *
 *  @param flashMode 闪光灯模式
 */
-(void)setFlashMode:(AVCaptureFlashMode )flashMode{
    [self changeDeviceProperty:^(AVCaptureDevice *captureDevice) {
        if ([captureDevice isFlashModeSupported:flashMode]) {
            [captureDevice setFlashMode:flashMode];
        }
    }];
}
/**
 *  设置聚焦模式
 *
 *  @param focusMode 聚焦模式
 */
-(void)setFocusMode:(AVCaptureFocusMode )focusMode{
    [self changeDeviceProperty:^(AVCaptureDevice *captureDevice) {
        if ([captureDevice isFocusModeSupported:focusMode]) {
            [captureDevice setFocusMode:focusMode];
        }
    }];
}
/**
 *  设置曝光模式
 *
 *  @param exposureMode 曝光模式
 */
-(void)setExposureMode:(AVCaptureExposureMode)exposureMode{
    [self changeDeviceProperty:^(AVCaptureDevice *captureDevice) {
        if ([captureDevice isExposureModeSupported:exposureMode]) {
            [captureDevice setExposureMode:exposureMode];
        }
    }];
}
/**
 *  设置聚焦点
 *
 *  @param point 聚焦点
 */
-(void)focusWithMode:(AVCaptureFocusMode)focusMode exposureMode:(AVCaptureExposureMode)exposureMode atPoint:(CGPoint)point{
    [self changeDeviceProperty:^(AVCaptureDevice *captureDevice) {
        if ([captureDevice isFocusModeSupported:focusMode]) {
            [captureDevice setFocusMode:AVCaptureFocusModeAutoFocus];
        }
        if ([captureDevice isFocusPointOfInterestSupported]) {
            [captureDevice setFocusPointOfInterest:point];
        }
        if ([captureDevice isExposureModeSupported:exposureMode]) {
            [captureDevice setExposureMode:AVCaptureExposureModeAutoExpose];
        }
        if ([captureDevice isExposurePointOfInterestSupported]) {
            [captureDevice setExposurePointOfInterest:point];
        }
    }];
}

/**
 *  添加点按手势，点按时聚焦
 */
-(void)addGenstureRecognizer{
    UITapGestureRecognizer *tapGesture=[[UITapGestureRecognizer alloc]initWithTarget:self action:@selector(tapScreen:)];
    [self.viewContainer addGestureRecognizer:tapGesture];
}
-(void)tapScreen:(UITapGestureRecognizer *)tapGesture{
    CGPoint point= [tapGesture locationInView:self.viewContainer];
    //将UI坐标转化为摄像头坐标
    CGPoint cameraPoint= [self.captureVideoPreviewLayer captureDevicePointOfInterestForPoint:point];
    [self setFocusCursorWithPoint:point];
    [self focusWithMode:AVCaptureFocusModeAutoFocus exposureMode:AVCaptureExposureModeAutoExpose atPoint:cameraPoint];
}

/**
 *  设置聚焦光标位置
 *
 *  @param point 光标位置
 */
-(void)setFocusCursorWithPoint:(CGPoint)point{
    self.focusCursor.center=point;
    self.focusCursor.transform=CGAffineTransformMakeScale(1.5, 1.5);
    self.focusCursor.alpha=1.0;
    [UIView animateWithDuration:1.0 animations:^{
        self.focusCursor.transform=CGAffineTransformIdentity;
    } completion:^(BOOL finished) {
        self.focusCursor.alpha=0;
        
    }];
}

- (UIInterfaceOrientationMask)supportedInterfaceOrientations
{
    return UIInterfaceOrientationMaskLandscape;
}

@end

遇到的主要问题：
我是ipad页面，当我翻转ipad的时候，该页面没有跟着转动，导致当我拿反pad的时候页面是个反的。
解决的办法就是上面的渲染页面我把它做了以下的操作：

[_captureVideoPreviewLayer connection].videoOrientation = (AVCaptureVideoOrientation)[[UIApplication sharedApplication] statusBarOrientation];