AVCaptureDevice是相机硬件的接口，用于配置底层硬件的属性，这些底层硬件包括前后置摄像头、麦克风、闪光灯等。
验证授权
1. 请求用户授权指定的媒体类型
为保护用户隐私，应用在使用相机或者麦克风时，总是需要用户授权才能正常使用。当应用第一次需要权限的媒体类型创建任何AVCaptureDeviceInput对象时，系统会自动显示一个alert以请求用户授权。在被授予任何访问权限之前，任何AVMediaType类型的AVCaptureDevice都将关闭静默音频样本或黑色视频帧。
调用下面方法，可以让应用直接获取用户授权，而不是需要等到创建AVCaptureDeviceInput对象时，系统自动显示一个alert以请求用户授权。
+ (void)requestAccessForMediaType:(AVMediaType)mediaType completionHandler:(void (^)(BOOL granted))handler
该方法有两个参数:
- 第一个参数mediaType: 媒体类型常量，可以是AVMediaTypeVideo和AVMediaTypeAudio，如果没有提供媒体类型或提供其他的媒体类型，都将抛出异常
- 第二个参数(void (^)(BOOL granted))handler: 获得用户相应后调用的块，如果用户授予使用硬件的权限，则granted返回YES,否则返回NO.注意块回调可能在任意线程，如果需要处理UI，需要切回主线程。
如果调用该方法之前，已经显示alert以请求用户授权，不管用户同意或者拒绝授权，该方法的回调都会立即放回用户曾经的授权结果，而不会再次显示一个alert请求用户授权。
应用程序必须在配置信息info.plist中提供使用NSCameraUsageDescription或NSMicrophoneUsageDescription信息的解释。iOS在最初请求用户许可时显示了这个解释，然后在设置应用程序中显示。在没有使用说明的情况下启动AVCaptureSession会引发异常。
2. 获取制定媒体类型的授权状态
为了获悉应用程序是否获取指定媒体类型的权限，应用可以调用下面的类方法获取授权状态:
+ (AVAuthorizationStatus)authorizationStatusForMediaType:(AVMediaType)mediaType;
该方法同步调用，会立即返回授权状态。如果此方法返回AVAuthorizationStatusNotDetermined，则可以调用+requestAccessForMediaType:completionHandler:以提示用户记录权限
授权状态AVAuthorizationStatus
- AVAuthorizationStatusNotDetermined: 用户尚未授权
- AVAuthorizationStatusRestricted:不允许用户访问媒体捕获设备，用户不能改变客户机的状态,可能由于活跃的限制,如家长控制，这个状态通常是看不到的,用于发现设备的类方法不会返回用户被限制访问的设备。
- AVAuthorizationStatusDenied:用户已经明确拒绝了应用访问捕获设备
- AVAuthorizationStatusAuthorized: 用户授予应用访问捕获设备的权限
媒体类型AVMediaType
- AVMediaTypeVideo: 指定视频
- AVMediaTypeAudio: 指定音频
- AVMediaTypeText: 指定文本
- AVMediaTypeClosedCaption: 指定闭路内容
- AVMediaTypeSubtitle: 指定字幕
- AVMediaTypeTimecode: 指定一个时间代码
- AVMediaTypeMetadata: 指定元数据
- AVMediaTypeMuxed: 指定混合媒体
- AVMediaTypeMetadataObject
- AVMediaTypeDepthData
通知
- AVCaptureDeviceWasConnectedNotification
当新设备可用时发送一个通知，通知对象是AVCaptureDevice实例，表示已可用的设备。 - AVCaptureDeviceWasDisconnectedNotification
当现有设备不可用时发送一个通知，通知对象是AVCaptureDevice实例，表示不可用的设备。
闪光灯
在光线不足的情况下，需要开启屏幕的闪光灯来进行补光，便于镜头可以捕捉更好的场景，拍摄出好的照片和视频
- iOS 10之前闪光灯设置
AVCaptureDevice *device = nil;
NSArray *inputs = self.session.inputs;
for (AVCaptureDeviceInput *input in inputs) {
if ([device.deviceType isEqual:AVMediaTypeVideo]) {
device = input.device;
}
}
NSError *errorProperty = nil;
if ([device hasFlash]) {
if ([device isFlashAvailable]) {
if ([device isFlashModeSupported:AVCaptureFlashModeOn]) {
BOOL result = NO;
result = [device lockForConfiguration:&errorProperty];
if (result) {
[device setFlashMode:AVCaptureFlashModeOn];
}else {
NSLog(@"ERROR : CONFIGURATION CAPTURE DEVICE FLASH FAILURE, ERROR CODE:%ld", (long)errorProperty.code);
}
[device unlockForConfiguration];
}else{
NSLog(@"ERROR : FLASH IS UNAVAILABLE BECAUSE THE DEVCICE OVERHEATS");
}
}else {
NSLog(@"ERROR : SOFTWARE DEVICE HAVE NO FLASH");
}
}
- iOS 10之后闪光灯设置
NSArray *outputs = self.session.outputs;
for (AVCaptureOutput *output in outputs) {
if ([output isMemberOfClass:[AVCapturePhotoOutput class]]) {
AVCapturePhotoOutput *photoOutput = (AVCapturePhotoOutput *)output;
BOOL flashSupported = [[photoOutput supportedFlashModes] containsObject:@(AVCaptureFlashModeAuto)];
if (flashSupported) {
AVCapturePhotoSettings *photoSettings = photoOutput.photoSettingsForSceneMonitoring;
photoSettings.flashMode = AVCaptureFlashModeAuto;
}else {
NSLog(@"ERROR : PHOTOOUTPUT CAN NOT SUPPORT AVCAPTUREMODE TYPE");
}
}
}
- 闪光灯类型
AVCaptureFlashModeOff = 0,//闪光灯关闭
AVCaptureFlashModeOn = 1,//闪光灯开启
AVCaptureFlashModeAuto = 2,//闪光灯自动
手电筒
在光线不是很暗的情况下我们可以用手机的LED灯当作手电筒使用。
AVCaptureDevice *device = nil;
NSArray *inputs = self.session.inputs;
for (AVCaptureDeviceInput *input in inputs) {
if ([device.deviceType isEqual:AVMediaTypeVideo]) {
device = input.device;
}
}
NSError *error = nil;
if ([device hasTorch]) {
if ([device isTorchAvailable]) {
if ([device isTorchModeSupported:AVCaptureTorchModeOn]) {
BOOL result = NO;
result = [device lockForConfiguration:&error];
if (result) {
[device setTorchMode:AVCaptureTorchModeOn];
}else {
NSLog(@"ERROR : CONFIGURATION DEVICE TORCH FAIL AND ERROR CODE %ld", (long)error.code);
}
error = nil;
// Torch light
result = [device setTorchModeOnWithLevel:0.5 error:&error];
if (!result) {
NSLog(@"ERROR : DEVICE SET TORCH FAILURE AND ERROR CODE %ld", error.code);
}
[device unlockForConfiguration];
}else {
NSLog(@"ERROR : DEVICE CAN NO SUPPORT TORCH");
}
}else {
NSLog(@"ERROR : SOFTHARE DEVICE TORCH IS UNAVAILABLE BECAUSE OVERHEATS");
}
}else {
NSLog(@"ERROR : SOFFHARE DEVICE HAS NO TORCH");
}
手电筒模式类型
AVCaptureTorchModeOff = 0,//关闭
AVCaptureTorchModeOn = 1,//打开
AVCaptureTorchModeAuto = 2,//自动
聚焦
- (void)focusAtPoint:(CGPoint)point {
AVCaptureDevice *device = [self activeCamera];
if (device.isFocusPointOfInterestSupported && [device isFocusModeSupported:AVCaptureFocusModeAutoFocus]) {
NSError *error;
// 锁定设备准备配置，如果获得了锁
if ([device lockForConfiguration:&error]) {
// 将focusPointOfInterest属性设置CGPoint
device.focusPointOfInterest = point;
device.focusMode = AVCaptureFocusModeAutoFocus;
// 释放该锁定
[device unlockForConfiguration];
} else {
if ([self.delegate respondsToSelector:@selector(deviceConfigurationFailedWithError:)]) {
[self.delegate deviceConfigurationFailedWithError:error];
}
}
}
}
- 聚焦类型
AVCaptureFocusModeLocked = 0,//锁定当前镜头位置
AVCaptureFocusModeAutoFocus = 1,//镜头自动调焦
AVCaptureFocusModeContinuousAutoFocus = 2,//镜头连续自动调焦
曝光
- (void)exposeAtPoint:(CGPoint)point {
AVCaptureDevice *device = [self activeCamera];
if (device.isExposurePointOfInterestSupported && [device isExposureModeSupported:AVCaptureExposureModeContinuousAutoExposure]) {
NSError *error;
if ([device lockForConfiguration:&error]) {
device.exposurePointOfInterest = point;
device.exposureMode = AVCaptureExposureModeContinuousAutoExposure;
[device unlockForConfiguration];
} else {
if ([self.delegate respondsToSelector:@selector(deviceConfigurationFailedWithError:)]) {
[self.delegate deviceConfigurationFailedWithError:error];
}
}
}
}
- 曝光设置类型
AVCaptureExposureModeLocked = 0,//锁定
AVCaptureExposureModeAutoExpose = 1,//自动对焦
AVCaptureExposureModeContinuousAutoExposure = 2,//实现连续自动对焦
白平衡
- 类型设置白平衡
AVCaptureDevice *device = nil;
NSArray *inputs = self.session.inputs;
for (AVCaptureDeviceInput *input in inputs) {
if ([device.deviceType isEqual:AVMediaTypeVideo]) {
device = input.device;
}
}
if ([device isWhiteBalanceModeSupported:AVCaptureWhiteBalanceModeAutoWhiteBalance]) {
NSError *error;
if ([device lockForConfiguration:&error]) {
[device setWhiteBalanceMode:AVCaptureWhiteBalanceModeAutoWhiteBalance];
}
[device unlockForConfiguration];
}
白平衡类型
AVCaptureWhiteBalanceModeLocked = 0,
AVCaptureWhiteBalanceModeAutoWhiteBalance = 1,
AVCaptureWhiteBalanceModeContinuousAutoWhiteBalance = 2,
- RGB设置白平衡
AVCaptureDevice *device = nil;
NSArray *inputs = self.session.inputs;
for (AVCaptureDeviceInput *input in inputs) {
if ([device.deviceType isEqual:AVMediaTypeVideo]) {
device = input.device;
}
}
float maxWhiteBalance = device.maxWhiteBalanceGain;
float redGain = MIN(2.0, maxWhiteBalance);
float greenGain = MIN(2.0, maxWhiteBalance);
float blueGain = MIN(2.0, maxWhiteBalance);
AVCaptureWhiteBalanceGains whiteBalanceGains = {
redGain,
greenGain,
blueGain
};
[device setWhiteBalanceModeLockedWithDeviceWhiteBalanceGains:whiteBalanceGains completionHandler:nil];
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