[笔记][08723] 使用 UIImagePickerController 拍照并保存到 Camera Roll

GitHub链接：https://github.com/1992chenlu/CameraDemo

效果图：

建好一个新的 Single View Application 之后，在 ViewController 中加一个 UIImageView 和一个 button，connect 到 .h 文件中。

1. 关于picker.allowsEditing

reference里面的那个例子设置为YES，其结果就是可以截取所拍照片的一部分，对应的UIImage对象是 info[UIImagePickerControllerEditedImage]。

2.关于保存

使用：

UIImageWriteToSavedPhotosAlbum(chosenImage, nil, nil, nil);

这里chosenImage是要保存的UIImage对象。得到它的方法是：

UIImage *chosenImage = info[UIImagePickerControllerOriginalImage];

3. 显示刚刚拍到的照片

self.imageView.image = chosenImage;

4. 关于一个bug

Snapshotting a view that has not been rendered results in an empty snapshot. Ensure your view has been rendered at least once before snapshotting or snapshot after screen updates.

Explanation: http://stackoverflow.com/questions/25884801/ios-8-snapshotting-a-view-that-has-not-been-rendered-results-in-an-empty-snapsho

代码：

//
//  ViewController.h
//  CameraDemo
//
//  Created by 鲁辰 on 7/5/15.
//  Copyright (c) 2015 ChenLu. All rights reserved.
//

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController <UIImagePickerControllerDelegate, UINavigationControllerDelegate>

@property (strong, nonatomic) IBOutlet UIImageView *imageView;
- (IBAction)takePhoto:(id)sender;
@property (weak, nonatomic) IBOutlet UIButton *takePhotoButton;

@end

//
//  ViewController.m
//  CameraDemo
//
//  Created by 鲁辰 on 7/5/15.
//  Copyright (c) 2015 ChenLu. All rights reserved.
//

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    
    if (![UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) {
        
        UIAlertView *myAlertView = [[UIAlertView alloc] initWithTitle:@"Error"
                                                              message:@"Device has no camera"
                                                             delegate:nil
                                                    cancelButtonTitle:@"OK"
                                                    otherButtonTitles: nil];
        
        [myAlertView show];
        
    }
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

#pragma mark - Image Picker Controller delegate methods

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {
    
    UIImage *chosenImage = info[UIImagePickerControllerOriginalImage];
    self.imageView.image = chosenImage;
    
    //Save photo to camera roll
    UIImageWriteToSavedPhotosAlbum(chosenImage, nil, nil, nil);
    
    [picker dismissViewControllerAnimated:YES completion:NULL];
    
    [self.view bringSubviewToFront:_takePhotoButton];
    
}

- (void)imagePickerControllerDidCancel:(UIImagePickerController *)picker {
    
    [picker dismissViewControllerAnimated:YES completion:NULL];
    
}

- (IBAction)takePhoto:(id)sender {
    UIImagePickerController *picker = [[UIImagePickerController alloc] init];
    picker.delegate = self;
    picker.allowsEditing = NO;
    picker.sourceType = UIImagePickerControllerSourceTypeCamera;
    
    [self presentViewController:picker animated:YES completion:NULL];
}
@end

Reference:

https://github.com/matthewmorton/Camera_App
http://stackoverflow.com/questions/14196012/how-to-force-a-uibutton-to-always-be-on-top