Question

我刚学习以下初学教程书，我有这段代码：

- (void) presentImagePickerUsingCamera:(BOOL)useCamera
{
    UIImagePickerController *cameraUI = [UIImagePickerController new];
    cameraUI.sourceType = (useCamera? UIImagePickerControllerSourceTypeCamera:
                                      UIImagePickerControllerSourceTypePhotoLibrary);

    cameraUI.mediaTypes = @[(NSString*)kUTTypeImage];
    cameraUI.delegate = self;
    [[self presentingViewController] dismissViewControllerAnimated:YES completion:nil]; 
    [self presentingViewController:cameraUI];
}

这是界面：

#import <UIKit/UIKit.h>
#import "MyWhatsit.h"

    @interface MSDetailViewController : UIViewController <UISplitViewControllerDelegate,
                                                           UIActionSheetDelegate,
                                                           UIImagePickerControllerDelegate,
                                                           UINavigationControllerDelegate>


    @property (strong,nonatomic) MyWhatsit* detailItem;
    @property (weak,nonatomic) IBOutlet UITextField *nameField;
    @property (weak,nonatomic) IBOutlet UITextField *locationField;
    @property (weak,nonatomic) IBOutlet UIImageView *imageView;
    - (IBAction)changeDetail:(id)sender;
    - (IBAction)chooseImage:(id)sender;
    - (void) presentImagePickerUsingCamera:(BOOL)useCamera;
    @end

给我错误：

code/MSDetailViewController.m:89:11: No visible @interface for 'MSDetailViewController' declares the selector 'presentingViewController:'

我确实试图找到像here

这样的答案

但没有任何帮助，我在这里做错了什么？

Answer 1

那是因为这一行：

[self presentingViewController:cameraUI];

没有这样的方法。您正在尝试设置显示视图控制器的控制器。它没有setter，因为它是readonly（https://developer.apple.com/library/ios/documentation/UIKit/Reference/UIViewController_Class/Reference/Reference.html#//apple_ref/occ/instp/UIViewController/presentingViewController）

如果你想设置它的值，@ property会给你这个（在变量名称之前设置）[self setSomeInstanceVariable: @"Something"];作为setter。所以，例如：

@property(nonatomic, strong)NSString *foo;

给你

[self foo]; //getter
[self setFoo:@"bar"]; // setter

如果要呈现视图控制器，则应使用以下方法：

presentViewControllerAnimated:completion

Answer 2

提出方法是：

- (void)presentViewController:(UIViewController *)viewControllerToPresent animated:(BOOL)flag completion:(void (^)(void))completion

所以在你的情况下：

[self presentViewController:cameraUI animated:YES completion:nil];

iOS presentsViewController给出No visible @interface错误

2 个答案: