iOS开发-调用系统相机和相册获取照片

前言：相信大家都知道大部分的app都是有我的模块的，而在我的模块基本都有用户的头像等信息，并且是可以更改头像的。那么今天小编给大家简单介绍一下iOS开发中如何调用系统相机拍照或者相册获取照片。要获取系统相机或者相册，我们需要使用到 UIImagePickerController 这个类。下面我们来看一下如何实现：

首先，需要遵循 UIImagePickerController 代理的两个协议： 。为什么是两个协议呢？你按着 command 键，点击 UIImagePickerController 的 delegate 就会发现其实这个代理遵循了两个协议。

#import "HeaderPhotoViewController.h"

@interface HeaderPhotoViewController () 

@property (nonatomic, strong) UIImageView * imageView;
@end

@implementation HeaderPhotoViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    self.navigationItem.title = @"设置头像";
    self.view.backgroundColor = [UIColor whiteColor];
    
    [self setNavigation];
    [self addSubviews];
    [self makeConstraintsForUI];
}

#pragma mark - set navigation

- (void)setNavigation {
    
    self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemCamera target:self action:@selector(selectPhoto:)];
}

#pragma mark - navitation item action

- (void)selectPhoto:(UIBarButtonItem *)itemCamera {

    //创建UIImagePickerController对象，并设置代理和可编辑
    UIImagePickerController * imagePicker = [[UIImagePickerController alloc] init];
    imagePicker.editing = YES;
    imagePicker.delegate = self;
    imagePicker.allowsEditing = YES;

    //创建sheet提示框，提示选择相机还是相册
    UIAlertController * alert = [UIAlertController alertControllerWithTitle:@"请选择打开方式" message:nil preferredStyle:UIAlertControllerStyleActionSheet];

    //相机选项
    UIAlertAction * camera = [UIAlertAction actionWithTitle:@"相机" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {

        //选择相机时，设置UIImagePickerController对象相关属性
        imagePicker.sourceType =  UIImagePickerControllerSourceTypeCamera;
        imagePicker.modalPresentationStyle = UIModalPresentationFullScreen;
        imagePicker.mediaTypes = @[(NSString *)kUTTypeImage];
        imagePicker.cameraCaptureMode = UIImagePickerControllerCameraCaptureModePhoto;
        //跳转到UIImagePickerController控制器弹出相机
        [self presentViewController:imagePicker animated:YES completion:nil];
    }];

    //相册选项
    UIAlertAction * photo = [UIAlertAction actionWithTitle:@"相册" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {

        //选择相册时，设置UIImagePickerController对象相关属性
        imagePicker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
        //跳转到UIImagePickerController控制器弹出相册
        [self presentViewController:imagePicker animated:YES completion:nil];
    }];

    //取消按钮
    UIAlertAction * cancel = [UIAlertAction actionWithTitle:@"取消" style:UIAlertActionStyleCancel handler:^(UIAlertAction * _Nonnull action) {
        
        [self dismissViewControllerAnimated:YES completion:nil];
    }];

    //添加各个按钮事件
    [alert addAction:camera];
    [alert addAction:photo];
    [alert addAction:cancel];

    //弹出sheet提示框
    [self presentViewController:alert animated:YES completion:nil];
}

#pragma mark - add subviews

- (void)addSubviews {
    
    [self.view addSubview:self.imageView];
}

#pragma mark - make constraints

- (void)makeConstraintsForUI {
    
    __weak typeof(self)weakSelf = self;
    
    [_imageView mas_makeConstraints:^(MASConstraintMaker *make) {
        
        make.size.mas_equalTo(CGSizeMake(Screen_Width, Screen_Width));
        make.centerX.mas_equalTo(weakSelf.view.mas_centerX);
        make.centerY.mas_equalTo(weakSelf.view.mas_centerY);
    }];
}

#pragma mark - imagePickerController delegate

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {
    
    [picker dismissViewControllerAnimated:YES completion:nil];
    //获取到的图片
    UIImage * image = [info valueForKey:UIImagePickerControllerEditedImage];
    _imageView.image = image;
}

#pragma mark - setter and getter

- (UIImageView *)imageView {
    
    if (!_imageView) {
        
        _imageView = [[UIImageView alloc] init];
        _imageView.backgroundColor = [UIColor greenColor];
        _imageView.contentMode = UIViewContentModeScaleAspectFill;
    }
    return _imageView;
}

@end

OK！demo的所有代码都已经给大家呈现出来了，最后一步就是配置plist文件，千万不要忘了这个，要不会崩的。plist文件里边添加调用相机的字段Privacy - Camera Usage Description 和调用相册的字段：Privacy - Photo Library Usage Description。万事俱备，就差一个测试的苹果手机了，相机的测试需要使用真机测试。

最后，希望能够帮助到有需要的猿友们，愿同是程序猿的我们能够共同学习进步，在开发的道路上越走越远！谢谢！