iOS调取本地相册更换头像

把调取相册获取图片与controller分离开，写成一个单独的类，在这里命名为NOVSelectPhotoManager

.h文件中

//声明一个协议NOVSelectPhotoManagerDeleagte
@protocol NOVSelectPhotoManagerDeleagte <NSObject>

@optional

//完成图片的选择时执行该协议方法
-(void)didChooseImage:(UIImage *)image;

@end

@interface NOVSelectPhotoManager : NSObject<UIImagePickerControllerDelegate>

@property(nonatomic,weak) id<NOVSelectPhotoManagerDeleagte> deleagte;

-(instancetype)initWithViewController:(UIViewController *)viewController;
//声明以下方法
//从相册中选取
-(void)selectImageWithAlbum;

//拍照
-(void)selectImageWithCamera;

@end

.m文件

• 声明一个viewcontroller对象(完成图片的选择时需要跳转回去的那个controller，也就是需要更换图片的界面)

@implementation NOVSelectPhotoManager{
    UIViewController *presentController;
}

-(instancetype)initWithViewController:(UIViewController *)viewController{
    self = [super init];
    if (self) {
        //在初始化方法中给presentController赋值
        presentController = viewController;
    }
    return self;
}

• 实现从相册中选取图片，进入图片选择界面，选择好图片后，自动执行UIImagePickerController的代理方法imagePickerController:didFinishPickingMediaWithInfo:

-(void)selectImageWithAlbum{
    UIImagePickerController *imagePickerController = [[UIImagePickerController alloc] init];
    imagePickerController.delegate = self;
    //允许编辑
    imagePickerController.allowsEditing = YES;
    //设置sourceType为UIImagePickerControllerSourceTypePhotoLibrary，代表调取相册
    imagePickerController.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
    if (presentController) {
        //从需要更换图片的界面跳转到选择图片界面
        [presentController presentViewController:imagePickerController animated:YES completion:nil];
        //选择完成后执行代理方法imagePickerController:idFinishPickingMediaWithInfo:
    }
}

• UIImagePickerController的代理方法，图片选择完成后执行该方法，可以从该代理方法中获取到所选择的图片信息。

-(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary<NSString *,id> *)info{
    //获取所选择的图片
    UIImage *image = info[@"UIImagePickerControllerEditedImage"];
    if (!image) {
        image = info[@"UIImagePickerControllerOriginalImage"];
    }
    if (_deleagte && [_deleagte respondsToSelector:@selector(didChooseImage:)]) {
        //获取到图片之后执行该方法，并将图片作为参数传给需要更换图片的viewcontroller
        [self.deleagte didChooseImage:image];
    }
    //跳转会需要更换图片的界面
    [picker dismissViewControllerAnimated:YES completion:nil];
}

info是字典类型，记录了所选择图片的信息，这里选择了UIImagePickerControllerEditedImage，也就是编辑之后的图片，若为空则取UIImagePickerControllerOriginalImage，即为原图片。

• 拍照（调取相机）

-(void)selectImageWithCamera{
    if (![UIImagePickerController isCameraDeviceAvailable:UIImagePickerControllerCameraDeviceRear]) {
        NSLog(@"no camera");
        return;
    }
    UIImagePickerController *imagePickerController = [[UIImagePickerController alloc] init];
    imagePickerController.delegate = self;
    imagePickerController.sourceType = UIImagePickerControllerSourceTypeCamera;
    [imagePickerController dismissViewControllerAnimated:YES completion:nil];
}

• viewcontroller 中

@interface MYViewController ()<NOVSelectPhotoManagerDeleagte>//实现
//声明一个调取相册的类
@property(nonatomic,strong) NOVSelectPhotoManager *photoManager;
@end

• 在viewcontroller添加UIAlertController，分别执行photograph，selectFromAlbum方法

    _actionController = [UIAlertController alertControllerWithTitle:nil message:nil preferredStyle:UIAlertControllerStyleAlert];
    UIAlertAction *photographAction = [UIAlertAction actionWithTitle:@"拍照" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
        //相机
        [self photograph];
    }];
    UIAlertAction *albumAction = [UIAlertAction actionWithTitle:@"从相册中选取" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
        //相册
        [self selectFromAlbum];
    }];
    UIAlertAction *cancelAction = [UIAlertAction actionWithTitle:@"取消" style:UIAlertActionStyleCancel handler:nil];
    [_actionController addAction:photographAction];
    [_actionController addAction:albumAction];
    [_actionController addAction:cancelAction];

• 实现方法selectFromAlbum

-(void)selectFromAlbum{
    if (!_photoManager) {
        //初始化并设置代理
        _photoManager = [[NOVSelectPhotoManager alloc] initWithViewController:self];
        _photoManager.deleagte = self;
    }
    //调用方法进行图片的选择
    [_photoManager selectImageWithAlbum];
}

• 实现方法photograph

 if (!_photoManager) {
        _photoManager = [[NOVSelectPhotoManager alloc] initWithViewController:self];
        _photoManager.deleagte = self;
    }
    [_photoManager selectImageWithCamera];

• 实现NOVSelectPhotoManager的代理方法didChooseImage:,并根据传过来的image更换图片

-(void)changeImageWithImage:(UIImage *)image{
    NSLog(@"=====%@",image);
    [_myView.headview.myImageButton setImage:image forState:UIControlStateNormal];
}