iOS 10之后改变的方法AVCaptureDeviceDiscoverySession使用

前言最近使用视频库<AVFoundation/AVFoundation.h>，遇到一个尴尬的问题

iOS 10 以前

//用来返回是前置摄像头还是后置摄像头

- (AVCaptureDevice *)cameraWithPostion:(AVCaptureDevicePosition)position{
    //返回和视频录制相关的默认设备
    NSArray *devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
    
    //遍历这些设备返回跟postion相关的设备
    for (AVCaptureDevice *device in devices) {
        if ([device position] == position) {
            return device;
        }
    }
    return nil;
}

iOS10 之后

- (AVCaptureDevice *)cameraWithPostion:(AVCaptureDevicePosition)position{
    AVCaptureDeviceDiscoverySession *devicesIOS10 = [AVCaptureDeviceDiscoverySession  discoverySessionWithDeviceTypes:@[AVCaptureDeviceTypeBuiltInWideAngleCamera] mediaType:AVMediaTypeVideo position];
    
    NSArray *devicesIOS  = devicesIOS10.devices;
    for (AVCaptureDevice *device in devicesIOS) {
        if ([device position] == position) {
            return device;
        }
    }
    return nil;
}