本文自作自用笔记，不喜勿喷，诚谢纠错。
调用相机首先需要设置info.plist文件获取相机访问权限。http://www.cnblogs.com/lc901221/p/6599644.html
调用时需要遵守两个协议UIImagePickerControllerDelegate和UINavigationControllerDelegate。
下面贴出调用相机的代码：
let imagePicker = UIImagePickerController()
//检测相机是否可用
let isAvailable = UIImagePickerController.isSourceTypeAvailable(UIImagePickerControllerSourceType.camera)
//必须首先设置sourceType 然后再设置其他属性 否则会出异常，提示sourceType 必须是 UIImagePickerControllerSourceTypeCamera
imagePicker.sourceType = .photoLibrary
if isAvailable {
imagePicker.sourceType = .camera
//如果有前置摄像头则调用前置摄像头
imagePicker.cameraDevice = UIImagePickerControllerCameraDevice.front
//是否显示控制栏,这里选择false会展示系统相机UI，如果要自定义可以将其隐藏
imagePicker.showsCameraControls=false
}
//代理
imagePicker.delegate = self
//打开相机
present(imagePicker, animated: true, completion: {
})
//是否可编辑
imagePicker.allowsEditing=false
下面是比较有用的两个协议方法：
//获取当前相机拍摄的照片，确定时的回调
func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : Any]) {
self.dismiss(animated: true, completion: nil)
if let photo = info[UIImagePickerControllerOriginalImage] as! UIImage?{
let image = UIImageView.init(frame: self.view.frame)
self.view.addSubview(image)
image.image = photo
}
}
//点击系统自定义取消按钮的回调
func imagePickerControllerDidCancel(_ picker: UIImagePickerController) {
self.dismiss(animated: true, completion: nil)
}