UIImage 的图像随时间变化

发布于 2024-11-06 23:35:00 字数 354 浏览 3 评论 0原文

我想更改 UIImageView 的图像，3 秒后返回到第一张图像...这是我的代码：

-(void)change: (UIImageView *)sender
{
    UIImage *image = [UIImage imageNAmed: @"anImage"];
    [sender setImage:image];
    [self performSelector: @selector(doNothing) withObject:nil afterDelay:3];
    [sender setImage: [UIImage imageNamed: @"firstImage"]];
}

它不起作用。

原文

I want to change an UIImageView's image and 3 seconds later go back to the first image...This is my code:

-(void)change: (UIImageView *)sender
{
    UIImage *image = [UIImage imageNAmed: @"anImage"];
    [sender setImage:image];
    [self performSelector: @selector(doNothing) withObject:nil afterDelay:3];
    [sender setImage: [UIImage imageNamed: @"firstImage"]];
}

It doesn't work.

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雨夜星沙 2024-11-13 23:35:00

尝试：

-(void)change: (UIImageView *)sender
{
    UIImage *image = [UIImage imageNAmed: @"anImage"];
    [sender setImage:image];
    [sender performSelector: @selector(setImage:) withObject:[UIImage imageNamed: @"firstImage"] afterDelay:3];
}

performSelector 安排选择器调用，并延迟一些。它不会延迟当前方法的执行

Try:

-(void)change: (UIImageView *)sender
{
    UIImage *image = [UIImage imageNAmed: @"anImage"];
    [sender setImage:image];
    [sender performSelector: @selector(setImage:) withObject:[UIImage imageNamed: @"firstImage"] afterDelay:3];
}

performSelector schedules selector call with some delay. It does not delay the execution of current method

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毁梦 2024-11-13 23:35:00

您也可以发布 doNothing 的代码吗？

如果 doNothing 确实什么都不做，那么所发生的情况是 doNothing 方法在以下行执行后 3 秒后被调用：

[self performSelector: @selector(doNothing) withObject:nil afterDelay:3];

But 事情是这样的，在您的 doNothing 方法被计划三秒后运行后，将立即执行以下行：

[sender setImage: [UIImage imageNamed: @"firstImage"]];

换句话说，方法执行不会等待您的 doNothing 方法完成，它只是继续，并且 doNothing 在单独的线程上运行。

Could you post the code for doNothing too please?

If doNothing really does nothing, then what's happening is the doNothing method is being called after 3 seconds from when the following line executes:

[self performSelector: @selector(doNothing) withObject:nil afterDelay:3];

But here's the thing, the following line is being executed straight after your doNothing method has been scheduled to run after three seconds:

[sender setImage: [UIImage imageNamed: @"firstImage"]];

In other words, the method execution doesn't wait around for your doNothing method to complete, it just continues, and doNothing is run on a separate thread.

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