Question

可以通过单击其他视图控制器内的按钮来更改图像吗？我使用此代码将数据从ViewController传递给SecondViewController。我想在同一个按钮上添加一个用于向SecondViewController添加图像的命令...请原谅我可怜的问题......

ViewController.h

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

@interface ViewController : UIViewController <SecondViewControllerDelegate> {

IBOutlet UITextField *userNameTextField;
}

@property (nonatomic, strong) UITextField *userNameTextField;

@end

ViewController.m

#import "ViewController.h"
#import "SecondViewController.h"

@interface ViewController ()

@end

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender{
if([segue.identifier isEqualToString:@"to2"]){
    SecondViewController *viewController = segue.destinationViewController;
    viewController.delegate = self;
}
}

- (void)done:(NSString *)name{
[self dismissViewControllerAnimated:YES completion:nil];
NSLog(@"Back in first ViewController, metod Done, with name=%@",name);
userNameTextField.text=name;
}

@end

SecondViewController.h

#import <UIKit/UIKit.h>

@protocol SecondViewControllerDelegate <NSObject>

-(void) done:(NSString*)someText;

@end

@interface SecondViewController : UIViewController {

IBOutlet UITextField *someText;
IBOutlet UIButton *returnButton;
id delegate;
}

@property (nonatomic, assign) id <SecondViewControllerDelegate> delegate;

@property (nonatomic, strong) UITextField *someText;

- (IBAction)returnButtonPressed:(id)sender;

@end

SecondViewController.m

#import "SecondViewController.h"

@interface SecondViewController ()

@end

@implementation SecondViewController

@synthesize someText;
@synthesize delegate = _delegate;

- (IBAction)returnButtonPressed:(id)sender {

[self.delegate done:someText.text];
}

@end

Answer 1

以下是一种适合您的方式：

只需在ViewController中使用图像设置NSNotification。按下按钮时在另一个viewController中触发通知。

图片视图控制器中的

：

    //in ViewDidLoad:
        [[NSNotificationCenter defaultCenter]addObserver:self selector:@selector(changeTheImage) name:@"CHANGE_THE_IMAGE" object:nil];


    //then elsewhere in the class:
    - (void)changeTheImage {
        //change your image here
    }


    //and in your dealloc, make sure you add this, or it will keep "observing"   
   [[NSNotificationCenter defaultCenter] removeObserver:self];

然后在按钮视图控制器中：

//have this as your button action (or add the line to your button action)
- (IBAction)yourButtonWasPressed:(id)sender {
    [[NSNotificationCenter defaultCenter]postNotificationName:@"CHANGE_THE_IMAGE" object:self];

Answer 2

更改另一个UIViewController的意思是什么。因为当您点击当前UIViewController时，这意味着当前位于顶部且可见。你所谓的另一个只能重叠不活动，或者它现在不存在。

因此，如果您想以某种方式从另一个UI更改UIImage，最简单的方法是将UIImage或图像文件名保存在全局存储区域，例如AppDelegate类，文件。单击时更改全局区域内容。在ui for image show中你可以添加一些代码

- (void)viewWillAppear:(BOOL)animated {
    //read and change UIImage content from global store
}

是你想要的吗？

更改两个View Controller之间的UIImage视图

2 个答案: