关于iOS中简单实现调用系统相机及相册功能

在iOS中要拍照和录制视频最简单的方式就是调用UIImagePickerController，UIImagePickerController继承与UINavigationController，需要使用代理方法时需要同时遵守这两个协议，以前可能比较多的是使用UIImagePickerController来选择相册图片或者拍摄图片，其实它的功能还能用来拍摄视频。

使用UIImagePickerController拍照或者拍视频主要以下几个步骤：

• 创建一个全局的UIImagePickerController对象。

• 指定UIImagePickerController的来源sourceType，是来自UIImagePickerControllerSourceTypeCamera相机，还是来自UIImagePickerControllerSourceTypePhotoLibrary相册。

• 然后是设置mediaTypes媒体类型，这是录制视频必须设置的选项，默认情况下是kUTTypeImage（注意：mediaTypes的设置是在MobileCoreServices框架下），同还可以设置一些其他视频相关的属性，例如：videoQuality视频的质量、videoMaximumDuration视频的最大录制时长（默认为10s），cameraDevice摄像头的方向（默认为后置相机）。

• 指定相机的捕获模式cameraCaptureMode，设置mediaTypes后在设置捕获模式，注意的是捕获模式需要在相机来源sourceType为相机时设置，否则会出现crash。

• 适时的展示UIImagePickerController，然后在相应的代理方法保存和获取图片或视频。

下面还是上代码吧，更加清晰明了...
首先需要导入以下用到的几个头文件，同时遵守两个代理方法

#import "ViewController.h"
#import 
#import 
#import 
@interface ViewController ()
{
    UIImagePickerController *_imagePickerController;
}

创建UIImagePickerController对象

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib
   
    _imagePickerController = [[UIImagePickerController alloc] init];
    _imagePickerController.delegate = self;
    _imagePickerController.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal;
    _imagePickerController.allowsEditing = YES;
    

从摄像头获取图片或视频

#pragma mark 从摄像头获取图片或视频
- (void)selectImageFromCamera
{
    _imagePickerController.sourceType = UIImagePickerControllerSourceTypeCamera;
    //录制视频时长，默认10s
    _imagePickerController.videoMaximumDuration = 15;

    //相机类型（拍照、录像...）字符串需要做相应的类型转换
    _imagePickerController.mediaTypes = @[(NSString *)kUTTypeMovie,(NSString *)kUTTypeImage];

    //视频上传质量
    //UIImagePickerControllerQualityTypeHigh高清
    //UIImagePickerControllerQualityTypeMedium中等质量
    //UIImagePickerControllerQualityTypeLow低质量
    //UIImagePickerControllerQualityType640x480
    _imagePickerController.videoQuality = UIImagePickerControllerQualityTypeHigh;

    //设置摄像头模式（拍照，录制视频）为录像模式
    _imagePickerController.cameraCaptureMode = UIImagePickerControllerCameraCaptureModeVideo;
    [self presentViewController:_imagePickerController animated:YES completion:nil];
}

从相册获取图片或视频

#pragma mark 从相册获取图片或视频
- (void)selectImageFromAlbum
{
    //NSLog(@"相册");
    _imagePickerController.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
    
    [self presentViewController:_imagePickerController animated:YES completion:nil];
}

在imagePickerController:didFinishPickingMediaWithInfo:代理方法中处理得到的资源，保存本地并上传...

#pragma mark UIImagePickerControllerDelegate
//该代理方法仅适用于只选取图片时
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingImage:(UIImage *)image editingInfo:(nullable NSDictionary *)editingInfo {
    NSLog(@"选择完毕----image:%@-----info:%@",image,editingInfo);
}

//适用获取所有媒体资源，只需判断资源类型
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info{
    NSString *mediaType=[info objectForKey:UIImagePickerControllerMediaType];
    //判断资源类型
    if ([mediaType isEqualToString:(NSString *)kUTTypeImage]){
        //如果是图片
        self.imageView.image = info[UIImagePickerControllerEditedImage];
        //压缩图片
        NSData *fileData = UIImageJPEGRepresentation(self.imageView.image, 1.0);
        //保存图片至相册
        UIImageWriteToSavedPhotosAlbum(self.imageView.image, self, @selector(image:didFinishSavingWithError:contextInfo:), NULL);
        //上传图片
        [self uploadImageWithData:fileData];
        
    }else{
        //如果是视频
        NSURL *url = info[UIImagePickerControllerMediaURL];
        //播放视频
        _moviePlayer.contentURL = url;
        [_moviePlayer play];
        //保存视频至相册（异步线程）
        NSString *urlStr = [url path];

        dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
            if (UIVideoAtPathIsCompatibleWithSavedPhotosAlbum(urlStr)) {
                
                UISaveVideoAtPathToSavedPhotosAlbum(urlStr, self, @selector(video:didFinishSavingWithError:contextInfo:), nil);
            }
        });
        NSData *videoData = [NSData dataWithContentsOfURL:url];
        //视频上传
        [self uploadVideoWithData:videoData];
    }
    [self dismissViewControllerAnimated:YES completion:nil];
}

图片和视频保存完毕后的回调

#pragma mark 图片保存完毕的回调
- (void) image: (UIImage *) image didFinishSavingWithError:(NSError *) error contextInfo: (void *)contextInf{
    
}

#pragma mark 视频保存完毕的回调
- (void)video:(NSString *)videoPath didFinishSavingWithError:(NSError *)error contextInfo:(void *)contextInf{
    if (error) {
        NSLog(@"保存视频过程中发生错误，错误信息:%@",error.localizedDescription);
    }else{
        NSLog(@"视频保存成功.");
    }
}

以上仅是简单功能的实现，还有例如切换前后摄像头、闪光灯设置、对焦、曝光模式等更多功能...