IOS SDK详解之拍照/相册（默认＋自定义拍照界面）

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本来要更新NSURLSession的UploadTask的，结果写那个Demo的时候想要写成拍照上传，然后就想到先写一个关于拍照的Demo吧。本文会先介绍下如何使用系统提供的界面拍照和选择相册，然后自定义拍照界面。注意，本文使用的是UIImagePickerController,所以不能完全的自定义，如果想要彻底的自定义拍照，建议选择AV Foundation这个框架来做

进入系统的拍照界面

一 使用系统提供的界面拍照和相册选择

第一步

保存一个UIImagePickerController的实例，然后适当的时候初始化始化。Demo选择在viewDidLoad初始化。让当前类实现UIImagePickerControllerDelegate,UINavigationControllerDelegate两个代理

@property (strong,nonatomic)UIImagePickerController * imagePikerViewController;
//初始化
self.imagePikerViewController = [[UIImagePickerController alloc] init];
self.imagePikerViewController.delegate = self;//通过代理来传递拍照的图片
self.imagePikerViewController.allowsEditing = YES;//允许编辑

第二步，通过ActionSheet来让用户选择是拍照还是到相册选择，然后模态的显示

[self presentViewController:self.imagePikerViewController animated:YES completion:NULL];

注意，要先判断相机是否可用，然后在进入相机（有可能相机坏了，或者在虚拟机上运行的）

UIAlertController * alertController = [UIAlertController alertControllerWithTitle: nil
                                                                              message: nil
                                                                       preferredStyle:UIAlertControllerStyleActionSheet];

    [alertController addAction: [UIAlertAction actionWithTitle: @"Take Photo" style: UIAlertActionStyleDefault handler:^(UIAlertAction *action) {
        if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]){
            self.imagePikerViewController.sourceType = UIImagePickerControllerSourceTypeCamera;
            [self presentViewController:self.imagePikerViewController animated:YES completion:NULL];
        }else{
            [self showAlertWithMessage:@"Camera is not available in this device or simulator"];
        }
    }]];
    [alertController addAction: [UIAlertAction actionWithTitle: @"Choose Existing Photo" style: UIAlertActionStyleDefault handler:^(UIAlertAction *action) {
        if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypePhotoLibrary]){
            self.imagePikerViewController.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
            [self presentViewController:self.imagePikerViewController animated:YES completion:NULL];
        }
    }]];
    [alertController addAction: [UIAlertAction actionWithTitle: @"Cancel" style: UIAlertActionStyleCancel handler:nil]];
    [self presentViewController: alertController animated: YES completion: nil];

第三部，代理函数处理拍照或者cancel事件

-(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info{
    UIImage * image = info[UIImagePickerControllerEditedImage];
    if (!image) {
        image = info[UIImagePickerControllerOriginalImage];
    }
    self.imageview.image = image;
    [self dismissViewControllerAnimated:YES completion:NULL];
}
-(void)imagePickerControllerDidCancel:(UIImagePickerController *)picker{
    [self dismissViewControllerAnimated:YES completion:NULL];
}

二 自定义拍照界面

UIImagePickerController的自定义界面比较简单，通过设置cameraOverlayView这个属性为自定义的View就能自定义。

第一步 创建一个View

创建xib文件

拖拽控件，进行autoLayout，最终效果如图

把fileOwner设置成CustomTakePhotoViewController

第二步 在显示拍照界面之前，把UI设置成自己想要的，注意，把属性

showsCameraControls设置为NO，不让默认的界面出现。

self.imagePikerViewController.sourceType = UIImagePickerControllerSourceTypeCamera;
self.imagePikerViewController.showsCameraControls = NO;
[[NSBundle mainBundle] loadNibNamed:@"CustomOverLayview" owner:self options:nil];
self.takePictureButton.layer.cornerRadius = 20;
self.takePictureButton.clipsToBounds = YES;
self.overlayView.frame = self.imagePikerViewController.cameraOverlayView.frame;
self.overlayView.backgroundColor = [UIColor clearColor];
self.imagePikerViewController.cameraOverlayView = self.overlayView;
self.overlayView = nil;
[self presentViewController:self.imagePikerViewController animated:YES completion:NULL];

第三步，为view上的控件添加动作

Segment Control负责切换前置摄像头和后置摄像头，为了流畅，在切换的时候显示动画。

- (IBAction)cameraSelect:(UISegmentedControl *)sender{
    NSInteger index = sender.selectedSegmentIndex;

    if (index == 0) {
        [UIView transitionWithView:self.imagePikerViewController.view duration:1.0 options:UIViewAnimationOptionAllowAnimatedContent | UIViewAnimationOptionTransitionCurlDown animations:^{
            self.imagePikerViewController.cameraDevice = UIImagePickerControllerCameraDeviceFront;
        } completion:NULL];
    }else{
        [UIView transitionWithView:self.imagePikerViewController.view duration:1.0 options:UIViewAnimationOptionAllowAnimatedContent | UIViewAnimationOptionTransitionCurlUp animations:^{
            [self.imagePikerViewController setCameraDevice:UIImagePickerControllerCameraDeviceRear];
        } completion:NULL];
    }
}

拍照的Button

- (IBAction)takePicture:(id)sender {
    [self.imagePikerViewController takePicture];
}

取消的Button

- (IBAction)cancelTakePicture:(id)sender {
    [self dismissViewControllerAnimated:YES completion:NULL];
}

第四步 在代理中处理图片

-(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info{
    UIImage * image = info[UIImagePickerControllerEditedImage];
    if (!image) {
        image = info[UIImagePickerControllerOriginalImage];
    }
    self.imageview.image = image;
    [self dismissViewControllerAnimated:YES completion:NULL];
}

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.

直接忽略就是了，没有任何影响，貌似是IOS 8的一个bug

http://download.csdn.net/detail/hello_hwc/8553539