Swift学习笔记（4）使用UIImagePickerController实现从设备图片库和照相机获取图片
设备图片库和照相机是图像的两个重要来源，使用UIKit中提供的图像选择器UIImagePickerController可以轻易地实现从设备图片库和照相机获取图片。
目录
Swift学习笔记4使用UIImagePickerController实现从设备图片库和照相机获取图片目录声明协议创建UIImagePickerControllerUIImagePickerControllerDelegate委托UINavigationControllerDelegate协议图片编辑iOS 9 中的新错误声明协议
UIViewController需声明实现如下两个协议
class viewController: UIViewController , UIImagePickerControllerDelegate , UINavigationControllerDelegate{...}
创建UIImagePickerController
定义一个UIImagePickerController
var imagePicker:UIImagePickerController!
创建一个UIButton，在其IBAction中添加代码
设备图片库：
if self.imagePicker == nil{self.imagePicker = UIImagePickerController()}self.imagePicker.delegate = self//设置图片来源为设备图片库self.imagePicker.sourceType = .PhotoLibraryself.presentViewController(self.imagePicker, animated: true, completion: nil)
照相机：
if UIImagePickerController.isSourceTypeAvailable(.Camera){if self.imagePicker == nil{self.imagePicker = UIImagePickerController()}self.imagePicker.delegate = self//设置图片来源为相机self.imagePicker.sourceType = .Cameraself.presentViewController(self.imagePicker, animated: true, completion: nil)}else{//弹出警告框let errorAlert = UIAlertController(title: "相机不可用", message: "", preferredStyle: UIAlertControllerStyle.Alert)let cancelAction = UIAlertAction(title: "确定", style: UIAlertActionStyle.Cancel, handler: nil)errorAlert.addAction(cancelAction)self.presentViewController(errorAlert, animated: true, completion: nil)}
UIImagePickerControllerDelegate委托
取消图片获取：
func imagePickerControllerDidCancel(picker: UIImagePickerController) {self.imagePicker = nilself.dismissViewControllerAnimated(true, completion: nil)}
完成图片获取：
func imagePickerController(picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : AnyObject]) {//从info中取出获取的原始图片let image = info[UIImagePickerControllerOriginalImage] as! UIImage self.imageView.image = image//设置图片显示模式self.imageView.contentMode = .ScaleAspectFillself.imagePicker.delegate = nilself.dismissViewControllerAnimated(true, completion: nil)}
UINavigationControllerDelegate协议
以下两个协议可以根据需求来选择是否实现
- navigationController:willShowViewController:animated- navigationController:didShowViewController:animated
图片编辑
如果要将原始图片进行编辑如缩放，裁剪等后再使用
则在创建UIImagePickerController时添加：
self.imagePicker.allowsEditing = true
然后将实现UIImagePickerControllerDelegate中的
let image = info[UIImagePickerControllerOriginalImage] as! UIImage
改为
let image = info[UIImagePickerControllerEditedImage] as! UIImage
iOS 9 中的新错误
如果在iOS 9 Xcode 7.1 以上的版本运行可能会报以下错误
_BSMachError: (os/kern) invalid capability (20)_BSMachError: (os/kern) invalid name (15)
解决方法：
打开Info.plist，将Localization native development region中的值由en改为United States
