效果图

如图，通过点击button进入UIalertcontroller，选择相册进入系统相册选择图片并上传到imageview上显示。话不多说，上代码：

#import "ViewController.m"

#import "ViewController.h"
#import <AVFoundation/AVFoundation.h>
#import <MediaPlayer/MediaPlayer.h>
@interface ViewController ()<UIImagePickerControllerDelegate, UINavigationControllerDelegate>{
    
    UIImagePickerController *_imagePickerController;
}
@property (strong, nonatomic) IBOutlet UIImageView *imgv;
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    
    _imagePickerController = [[UIImagePickerController alloc] init];
    _imagePickerController.delegate = self;
    //跳转动画效果
    _imagePickerController.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal;
    _imagePickerController.allowsEditing = YES;
    
}

- (IBAction)butt:(id)sender {
    
    UIAlertController *alertCtl =[[UIAlertController alloc]init];
    
    UIAlertAction *cancel =[UIAlertAction actionWithTitle:@"取消" style:UIAlertActionStyleCancel handler:^(UIAlertAction * _Nonnull action) {
        NSLog(@"cancel");
    }];
    UIAlertAction *xiangji =[UIAlertAction actionWithTitle:@"相机" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
        NSLog(@"xiangji");
        
        [self openCamera];
    }];
    UIAlertAction *xiangce =[UIAlertAction actionWithTitle:@"相册" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
        NSLog(@"xiangce");
        
        [self openPhotoLibrary];
    }];
    
    [alertCtl addAction:cancel];
    [alertCtl addAction:xiangji];
    [alertCtl addAction:xiangce];
    
    [self presentViewController:alertCtl animated:YES completion:nil];
}

/**
 *  调用照相机
 */
- (void)openCamera
{

    //判断是否可以打开照相机
    if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]){
        //摄像头
        _imagePickerController.sourceType = UIImagePickerControllerSourceTypeCamera;
        [self presentViewController:_imagePickerController animated:YES completion:nil];
    }
    else{
        NSLog(@"没有摄像头");
    }
}
/**
 *  打开相册
 */
-(void)openPhotoLibrary{

    // 进入相册
    if([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypePhotoLibrary])
    {
        _imagePickerController.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
        [self presentViewController:_imagePickerController animated:YES completion:^{
            NSLog(@"打开相册");
        }];
    }else{
        NSLog(@"不能打开相册");
    }
}
#pragma mark - UIImagePickerControllerDelegate
// 拍照完成回调
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingImage:(UIImage *)image editingInfo:(nullable NSDictionary<NSString *,id> *)editingInfo NS_DEPRECATED_IOS(2_0, 3_0){
    
    NSLog(@"finish..");
    if(picker.sourceType == UIImagePickerControllerSourceTypeCamera)
    {
        //图片存入相册
        UIImageWriteToSavedPhotosAlbum(image, nil, nil, nil);
    }
    self.imgv.image =image;
    [self dismissViewControllerAnimated:YES completion:nil];
}

//进入拍摄页面点击取消按钮
- (void)imagePickerControllerDidCancel:(UIImagePickerController *)picker{
    [self dismissViewControllerAnimated:YES completion:nil];
}

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

@end

接下来在info.plist文件中添加NSPhotoLibraryUsageDescription和NSCameraUsageDescription用于获取手机的相机和相册的权限，运行。

需要注意的是，模拟器上并不支持相机，选择相册，选择图片，完成。

完成.png