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[英]How to change image of UIImageView that is inside a UIButton programmatically?
[英]Change image in UIImageView when UIButton is pressed programmatically
我試圖在按下UIButton時更改imageview內的圖像。 更改圖片之前,我至少需要單擊三四次。 怎么了 ?
這是我正在使用的代碼
@interface ARViewController ()
@property (nonatomic, strong) NSMutableArray *pepsiPhotos;
@property (nonatomic, strong) UIImageView *imageView;
@end
@implementation ARViewController
{
IBOutlet UIView *overlayView;
int currentImageIndex;
}
@synthesize imageView;
- (void)viewDidLoad
{
[super viewDidLoad];
_pepsiPhotos = [NSMutableArray arrayWithObjects:@"pepsican.jpeg",
@"pepsilight.jpeg", @"7up.jpeg", @"mirinda.jpeg", nil];
overlayView = [[UIView alloc] initWithFrame:CGRectMake(50.f, 80.f, 240.f, 275.f)];
[overlayView setHidden:YES];
imageView = [[UIImageView alloc] initWithFrame:CGRectMake(10.f, 20.f, 200.f, 150.f)];
[overlayView addSubview:imageView];
[self.view addSubview:overlayView];
currentImageIndex = 0;
[self showImages];
}
-(void) showImages
{
//
[overlayView setHidden:NO];
[overlayView setBackgroundColor:[UIColor clearColor]];
[overlayView setUserInteractionEnabled:YES];
UIButton *nextButton = [UIButton buttonWithType:UIButtonTypeRoundedRect];
nextButton.frame = CGRectMake(165.f, 260.f, 40.f, 40.f);
[nextButton setTitle:@"Next" forState:UIControlStateNormal];
[nextButton addTarget:self action:@selector(nextButtonPressed:) forControlEvents:UIControlEventTouchDown];
[nextButton setUserInteractionEnabled:YES];
[overlayView addSubview:nextButton];
[overlayView bringSubviewToFront:nextButton];
UIButton *previousButton = [UIButton buttonWithType:UIButtonTypeRoundedRect];
previousButton.frame = CGRectMake(0, 260.f, 40.f, 40.f);
[previousButton setTitle:@"Last" forState:UIControlStateNormal];
[previousButton addTarget:self action:@selector(previousButtonPressed:) forControlEvents:UIControlEventTouchDown];
[previousButton setUserInteractionEnabled:YES];
[overlayView addSubview:previousButton];
[imageView setImage:[UIImage imageNamed:[_pepsiPhotos objectAtIndex:currentImageIndex]]];
[overlayView addSubview:imageView];
[self.view addSubview:overlayView];
}
-(IBAction)nextButtonPressed:(id)sender
{
if (currentImageIndex < [_pepsiPhotos count] -1)
{
currentImageIndex++;
[self performSelectorOnMainThread:@selector(showNextImage) withObject:nil waitUntilDone:NO];
}
}
-(IBAction)previousButtonPressed:(id)sender
{
if (currentImageIndex > 0)
{
currentImageIndex--;
[self performSelectorOnMainThread:@selector(showNextImage) withObject:nil waitUntilDone:NO];
}
}
-(void)showNextImage
{
[imageView setImage:[UIImage imageNamed:[_pepsiPhotos objectAtIndex:currentImageIndex]]];
[overlayView addSubview:imageView];
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
@end
一個問題是您說的是performSelectorOnMainThread:
如果這是您的按鈕操作方法,你是在主線程上 。 只要回應即可,但您想回應。
說performSelectorOnMainThread:
當您已經在主線程上時,實際上可能會導致延遲,因為現在我們必須等待主線程變為空閑后才能運行代碼。
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