此工程使用Storyboard来实现的：
#import "ViewController.h"
@interface ViewController ()<UIImagePickerControllerDelegate,UINavigationControllerDelegate>
@property (strong, nonatomic) IBOutlet UIButton *buttoon;
@property (strong, nonatomic) IBOutlet UIImageView *imageView;
@end
@implementation ViewController
- (IBAction)btAction:(UIButton *)sender {
//创建提示框 控制器
UIAlertController *alertC = [UIAlertController alertControllerWithTitle:@"提示框" message:nil preferredStyle:UIAlertControllerStyleActionSheet];
//创建相机的点击事件按钮
UIAlertAction *alertA = [UIAlertAction actionWithTitle:@"相机" style:UIAlertActionStyleDestructive handler:^(UIAlertAction *action){
//判断系统设备是否存在相机，有调用 没有提醒用户
if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) {
//如果有摄像头 ,创建相机
UIImagePickerController *picker = [[ UIImagePickerController alloc] init];
//指定数据来源，来自于相机
picker.sourceType = UIImagePickerControllerSourceTypeCamera;
picker.delegate = self;
picker.allowsEditing = YES;//允许编辑
//使用模态弹出相机
[self presentViewController:picker animated:YES completion:nil];
}else {
//没有摄像头提醒用户，您的设备没有摄像头
UIAlertController *controller = [UIAlertController alertControllerWithTitle:@"您的设备没有摄像头" message:nil preferredStyle:UIAlertControllerStyleAlert];
UIAlertAction *action = [UIAlertAction actionWithTitle:@"确定" style:UIAlertActionStyleDefault handler:nil];
[controller addAction:action];
[self presentViewController:controller animated:YES completion:nil];
}
}];
[alertC addAction:alertA];//添加到提示框
//创建相册的点击事件按钮，
UIAlertAction *action = [ UIAlertAction actionWithTitle:@"相册" style:UIAlertActionStyleDefault handler:^(UIAlertAction *action){
UIImagePickerController *picker = [[UIImagePickerController alloc] init];
picker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;//指定数据来源是相册
picker.delegate = self;
picker.allowsEditing = YES;
[self presentViewController:picker animated:YES completion:nil];
}];
[alertC addAction:action];
[self presentViewController:alertC animated:YES completion:nil];
}
//选取图片之后执行的方法
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary<NSString *,id> *)info{
NSLog(@"%@",info);//是个字典
//通过字典的key值来找到图片
UIImage *image = [info objectForKey:UIImagePickerControllerOriginalImage];/选取的是原始图片。还有其他的样式；如编辑的图片：UIImagePickerControllerEditedImage
//并且赋值给声明好的imageView
self.imageView.image = image;
//最后模态返回 最初的 控制器
[picker dismissViewControllerAnimated:YES completion:nil];
}
注意：使用时要接受两个协议：<UIImagePickerControllerDelegate,UINavigationControllerDelegate>，创建UIAlertController和UIAlertAction的初始化方法名的区别，其他就是其样式的选取的区别，根据自己的需求来选择样式。弹出提示框使用的是，模态的方法弹出，返回时同样使用的是模态，方法名要熟记。