拍摄照片后选择"使用照片"时,使用UIImagePickerController的应用程序会冻结

Question

我正在制作一个简单的照片和视频捕捉应用程序.该应用程序成功允许用户在按下按钮时拍摄照片或视频.但是,只要您完成拍摄照片或视频,它就会提供2个选项:"重拍"和"使用照片"或"使用视频",具体取决于您使用的是哪一个.

如果用户点击"重拍",则只需让他们重新拍摄新照片或视频,但当用户点按"使用照片"或"使用视频"时,屏幕会冻结.

如果我退出冻结的应用程序并查看我的相机胶卷,我刚刚使用该应用程序拍摄的照片已成功保存.因此,当您点击"使用照片"按钮时,尽管应用程序屏幕冻结,但它仍然成功保存到相机胶卷.

有人告诉我"它冻结了,因为它需要一些时间来保存照片并且它正在主线程上运行.你可以使用ALAssetLibrary来修复冻结问题."

但是,我不熟悉ALAssetLibrary或者为何在这种情况下有用的理论.我只是浏览了一些文档,但我仍然迷失了.

任何帮助将不胜感激.

这是我到目前为止的代码:

ViewController.h:

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController <UINavigationControllerDelegate, UIImagePickerControllerDelegate>

@property UIImagePickerController * pickerController;

-(IBAction)showCameraUI;

@end

ViewController.m:

#import "ViewController.h"
#import <MobileCoreServices/MobileCoreServices.h>


@interface ViewController () <UINavigationControllerDelegate, UIImagePickerControllerDelegate>

//The above are the 2 delegates required for creating a media capture/camera app.

- (void)imagePickerController:pickerController didFinishPickingMediaWithInfo:(NSDictionary *)info;


@end

@implementation ViewController

- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.

[UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera];
[UIImagePickerController availableMediaTypesForSourceType:UIImagePickerControllerSourceTypeCamera];

NSLog(@"%ld", (long)UIImagePickerControllerSourceTypeCamera);

}

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

-(IBAction)showCameraUI{

UIImagePickerController * pickerController = [[UIImagePickerController alloc]init];

pickerController.mediaTypes = [UIImagePickerController  availableMediaTypesForSourceType:UIImagePickerControllerSourceTypeCamera];

pickerController.sourceType = UIImagePickerControllerSourceTypeCamera;

pickerController.delegate = self;

[self presentViewController:pickerController animated:YES completion:nil];

}

- (void)imagePickerController:pickerController didFinishPickingMediaWithInfo:(NSDictionary *)info
{
// saves the photo you just took

NSString *mediaType = [info objectForKey:UIImagePickerControllerMediaType];

if ([mediaType isEqualToString:(NSString *)kUTTypeImage])
{
    UIImage *image = [info objectForKey:UIImagePickerControllerOriginalImage];
    UIImageWriteToSavedPhotosAlbum(image,nil,nil,nil);
}

}

- (void)imagePickerControllerDidCancel:pickerController
{
[self dismissViewControllerAnimated:YES completion:nil];
}

@end