在按钮按下后出现图像

Question

我试图改变背景颜色，并在按下按钮时使图像出现在屏幕上。我可以改变颜色，但我无法看到要显示的图像的痕迹。我不知道如何将图像放在屏幕上。我正在使用iOS 5和故事板，但我没有将UIImageView添加到故事板，因为我希望它出现。

我ViewController.h

#import <UIKit/UIKit.h> 

@interface ViewController : UIViewController 
- (IBAction)changeButton:(id)sender; 

@end 

我ViewController.m

#import "ViewController.h" 

@interface ViewController() 

@end 

@implementation ViewController 

- (void)viewDidLoad 
{ 
    [super viewDidLoad]; 
    // Do any additional setup after loading the view, typically from a nib. 

} 

- (void)didReceiveMemoryWarning 
{ 
    [super didReceiveMemoryWarning]; 
    // Dispose of any resources that can be recreated. 
} 

-(void)colorchange 
{ 
    self.view.backgroundColor = [UIColor greenColor]; 
} 

-(void)imageShow 
{ 
    UIImage *image = [UIImage imageNamed:@"logo-tag-centered.pmg"]; 
    UIImageView *imgView = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, 0, 0)]; 
    [imgView setImage:image]; 

} 

- (IBAction)changeButton:(id)sender 
{ 
    [self colorchange]; 
    [self imageShow]; 

} 
@end 

任何帮助将不胜感激！谢谢！

Answer 1

您必须将图像视图添加到您的视图控制器的视图。

- (void)showImage 
{ 
    UIImage *image = [UIImage imageNamed:@"logo-tag-centered.png"]; 
    UIImageView *imgView = [[UIImageView alloc] initWithImage:image]; 
    imgView.center = CGPointMake(self.view.bounds.size.width/2.0f, self.view.bounds.size.height/2.0f); 
    [self.view addSubview:imgView]; 
} 

Answer 2

您还没有将图像视图添加到主视图的任何位置。你可以这样做：

- (void)viewDidLoad 
{ 
    [super viewDidLoad]; 
    UIImage *image = [UIImage imageNamed:@"logo-tag-centered.pmg"]; 
    UIImageView *imgView = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, 0, 0)]; 
    [imgView setImage:image]; 
    [imgView setHidden:YES]; 
    [self.view addSubview:imgView]; 
} 
-(void)imageShow 
{ 
    [imgView setHidden:NO]; 
} 
- (IBAction)changeButton:(id)sender 
{ 
    [self colorchange]; 
    [self imageShow]; 
}