图片多选的实现 分为两部分
1 调用相机拍照添加图片
2 打开相册添加图片

1 使用相机添加图片

-(void)addimagePicker{
// 遵守UIImagePickerControllerDelegate 协议创建imagePicker对象
    UIImagePickerController *pickercontroller = [[UIImagePickerController alloc]init];
    pickercontroller.allowsEditing = YES ;
    pickercontroller.delegate = self ;
    _pickercontroller = pickercontroller ;
}

调用相机时进行如下设置
_pickercontroller.sourceType = UIImagePickerControllerSourceTypeCamera ;
            // 默认是打开相机 也可以设置为录制视频
            _pickercontroller.cameraCaptureMode = UIImagePickerControllerCameraCaptureModePhoto ;
            [self presentViewController:_pickercontroller animated:YES completion:nil];

实现imagePicker 的代理方法（拍照完成获取image）
// 用户选中某条媒体信息之后的处理
-(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary<NSString *,id> *)info{
    // 获取媒体类型（相机 or 相册 or 视频 ）
    NSString *mediatype = [info objectForKey:UIImagePickerControllerMediaType];
    if ([mediatype isEqualToString:@"public.image"]) {
        UIImage *image = [info objectForKey:UIImagePickerControllerOriginalImage];
        // 将拍好的图片存入系统相册
        UIImageWriteToSavedPhotosAlbum(image, nil, nil, nil);
        // 对图片数据进行压缩
        NSData *data = UIImageJPEGRepresentation(image, 0.2);     
        UIImage *resultimage = [[UIImage alloc]initWithData:data];
}

打开相册添加图片
使用第三方QBImagePicker 实现
1 遵守协议
QBImagePickerControllerDelegate
2 创建图片选择器对象

-(void)addQBImagePicker{
    QBImagePickerController *imagePickerController = [QBImagePickerController new];
    imagePickerController.delegate = self;
    imagePickerController.mediaType = QBImagePickerMediaTypeAny;
    imagePickerController.allowsMultipleSelection = 20;
    imagePickerController.showsNumberOfSelectedAssets = YES;
    _qbimagepicker = imagePickerController ;
}

3 实现代理方法

- (void)qb_imagePickerController:(QBImagePickerController *)imagePickerController didFinishPickingAssets:(NSArray *)assets
{
    PHImageRequestOptions *options = [[PHImageRequestOptions alloc] init];
    options.deliveryMode = PHImageRequestOptionsDeliveryModeHighQualityFormat;

    for (PHAsset *asset in assets) {
        
        [[PHImageManager defaultManager] requestImageForAsset:asset targetSize:[UIScreen mainScreen].bounds.size contentMode:PHImageContentModeAspectFit options:options resultHandler:^(UIImage *result, NSDictionary *info) {
            NSDictionary *dic = @{@"image":result,@"isselect":@"0"};
            [_selectArr addObject:dic];
            if (_selectArr.count == assets.count) {
                // 先确定范围 range
                NSRange range = NSMakeRange(_dataArr.count-1,_selectArr.count);
                // 创建一个indexset对象
                NSIndexSet *set = [NSIndexSet indexSetWithIndexesInRange:range];
                // 插入数组中的元素
            [_dataArr insertObjects:_selectArr atIndexes:set];
            [_selectArr removeAllObjects];
            [_collectionView reloadData];
            }
        }];
    }

    [self dismissViewControllerAnimated:YES completion:NULL];
}

- (void)qb_imagePickerControllerDidCancel:(QBImagePickerController *)imagePickerController
{
    [self dismissViewControllerAnimated:YES completion:NULL];
}