如何将自身作为不同UIImagePickerController的代理并区分来源

哈哈，这个问题我太有共鸣了！刚接触iOS的时候，也纠结过为啥不像Android那样有个现成的requestCode用来区分请求。不过别慌，咱们有好几种办法能实现类似的效果，给你详细说说：

方法1：给UIImagePickerController加自定义标识（关联对象） #

这个方法的核心是给每个图片选择器对象绑定一个自定义的标识，就像Android的requestCode一样，回调时直接从picker对象上取出来判断，非常灵活安全。

首先定义一个关联用的唯一key：

static char kPickerRequestCodeKey;

然后在启动选择器的两个方法里，给picker设置不同的标识：

- (void)openAvatarPicker {
    UIImagePickerController *picker = [[UIImagePickerController alloc] init];
    picker.delegate = self;
    // 给这个picker绑定标识1，代表是头像选择器
    objc_setAssociatedObject(picker, &kPickerRequestCodeKey, @(1), OBJC_ASSOCIATION_RETAIN_NONATOMIC);
    [self presentViewController:picker animated:YES completion:nil];
}

- (void)openCoverPicker {
    UIImagePickerController *picker = [[UIImagePickerController alloc] init];
    picker.delegate = self;
    // 给这个picker绑定标识2，代表是封面选择器
    objc_setAssociatedObject(picker, &kPickerRequestCodeKey, @(2), OBJC_ASSOCIATION_RETAIN_NONATOMIC);
    [self presentViewController:picker animated:YES completion:nil];
}

最后在代理回调里取出标识，区分处理：

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary<UIImagePickerControllerInfoKey,id> *)info {
    NSNumber *requestCode = objc_getAssociatedObject(picker, &kPickerRequestCodeKey);
    if ([requestCode integerValue] == 1) {
        // 处理头像相关逻辑
        UIImage *selectedAvatar = info[UIImagePickerControllerOriginalImage];
        // ...你的操作
    } else if ([requestCode integerValue] == 2) {
        // 处理封面相关逻辑
        UIImage *selectedCover = info[UIImagePickerControllerOriginalImage];
        // ...你的操作
    }
    [picker dismissViewControllerAnimated:YES completion:nil];
}

方法2：用控制器属性记录当前选择器类型 #

如果你的场景里不会同时弹出多个图片选择器（大部分情况都是这样），那用一个属性记录当前启动的是哪个选择器会更简单。

先定义一个枚举来区分类型：

typedef NS_ENUM(NSInteger, PickerType) {
    PickerTypeAvatar,
    PickerTypeCover
};

@interface YourViewController ()
@property (nonatomic, assign) PickerType currentPickerType;
@end

启动选择器时设置对应的类型：

- (void)openAvatarPicker {
    UIImagePickerController *picker = [[UIImagePickerController alloc] init];
    picker.delegate = self;
    self.currentPickerType = PickerTypeAvatar;
    [self presentViewController:picker animated:YES completion:nil];
}

- (void)openCoverPicker {
    UIImagePickerController *picker = [[UIImagePickerController alloc] init];
    picker.delegate = self;
    self.currentPickerType = PickerTypeCover;
    [self presentViewController:picker animated:YES completion:nil];
}

回调时根据属性判断：

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary<UIImagePickerControllerInfoKey,id> *)info {
    if (self.currentPickerType == PickerTypeAvatar) {
        // 处理头像逻辑
    } else if (self.currentPickerType == PickerTypeCover) {
        // 处理封面逻辑
    }
    [picker dismissViewControllerAnimated:YES completion:nil];
}

小总结 #

如果你的项目有复杂场景（比如可能同时弹出多个选择器），优先用关联对象的方法，每个picker自己带标识，不会互相干扰；如果只是普通的单一场景，用控制器属性记录的方式更省事，代码也更简洁。

内容的提问来源于stack exchange，提问作者John