UIImagePickerController 的一般用法

步骤 1：创建控制器，设置委托，并遵守协议

//Swift
class ImageUploadViewController: UIViewController, UIImagePickerControllerDelegate, UINavigationControllerDelegate {
    
    let imagePickerController = UIImagePickerController()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        imagePickerController.delegate = self
    }
}

//Objective-C
@interface ImageUploadViewController : UIViewController <UIImagePickerControllerDelegate,UINavigationControllerDelegate> {

    UIImagePickerController *imagePickerController;

}

@end

@implementation ImageUploadViewController

- (void)viewDidLoad {

    [super viewDidLoad];

    imagePickerController.delegate = self;

}

@end

注意：我们实际上不会实现 UINavigationControllerDelegate 中定义的任何内容，但是 UIImagePickerController 继承自 UINavigationController 并改变了 UINavigationController 的行为。因此，我们仍然需要说我们的视图控制器符合 UINavigationControllerDelegate。

第 2 步：每当你需要展示 UIImagePickerController：

//Swift
self.imagePickerController.sourceType = .Camera // options: .Camera , .PhotoLibrary , .SavedPhotosAlbum
self.presentViewController(self.imagePickerController, animated: true, completion: nil)

//Objective-C
imagePickerController.sourceType = UIImagePickerControllerSourceTypeCamera; // options: UIImagePickerControllerSourceTypeCamera, UIImagePickerControllerSourceTypePhotoLibrary, UIImagePickerControllerSourceTypeSavedPhotosAlbum
[self presentViewController:imagePickerController animated:YES completion:nil];

第 3 步：实现委托方法：

//Swift
func imagePickerController(picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : AnyObject]) {
    if let pickedImage = info[UIImagePickerControllerOriginalImage] as? UIImage {
        // Your have pickedImage now, do your logic here
    }
    self.dismissViewControllerAnimated(true, completion: nil)
}

func imagePickerControllerDidCancel(picker: UIImagePickerController) {
    self.dismissViewControllerAnimated(true, completion: nil)
}

//Objective-C
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {

   UIImage *pickedImage = info[UIImagePickerControllerOriginalImage];

    if (pickedImage) {
    
        //You have pickedImage now, do your logic here
    
    }

    [self dismissViewControllerAnimated:YES completion:nil];

}

- (void)imagePickerControllerDidCancel:(UIImagePickerController *)picker {

    [self dismissViewControllerAnimated:YES completion:nil];

}