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我必须在一个屏幕上交换四个图像。图像只能在左/右/上/下方向交换，不能对角交换。例如，第 1 张图像可以与其右侧和下方的图像交换，第 2 幅图像只能与其左侧和下方的图像交换，以此类推。任何人都可以请帮助我如何做到这一点。谢谢

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2 回答 2

0

添加滑动手势识别器。当用户滑动时确定哪个方向并处理图像交换。

[编辑] - 想象一个正方形分成四个相等的部分。左上部分的索引为 0，右上部分的索引为 1，左下部分的索引为 2，最后右下部分的索引为 3。下面的代码检查当前索引，并从中确定图像是否可以进行交换，如果没有，它什么也不做。

这段代码来自我的脑海，所以可能存在语法错误，但逻辑是合理的（我希望 :D ）。

- (void) viewDidLoad {
// turn on user interaction on the image view as its off by default.
[self.imageView setUserInteractionEnabled:TRUE];

UISwipeGestureRecognizer *recognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleSwipe:)];
[recognizer setDirection:(UISwipeGestureRecognizerDirectionRight | UISwipeGestureRecognizerDirectionDown | UISwipeGestureRecognizerDirectionLeft | UISwipeGestureRecognizerDirectionUp)];
[self.imageView addGestureRecognizer:recognizer];

self.currentImageIndex = 0;
self.images = [NSArray arrayWithObjects:[UIImage imageNamed:@"top-left"],[UIImage imageNamed:@"top-right"],[UIImage imageNamed:@"bottom-left"],[UIImage imageNamed:@"top-right"],nil];

}


-(void)handleSwipeFrom:(UISwipeGestureRecognizer *)recognizer {

if (recognizer.direction == UISwipeGestureRecognizerDirectionRight) {

if (self.currentImageIndex == 0 || self.currentImageIndex == 2) self.currentImageIndex++; // change to image to the right
else return; // do nothing

}
else if (recognizer.direction == UISwipeGestureRecognizerDirectionLeft) {

if (self.currentImageIndex == 1 || self.currentImageIndex == 3) self.currentImageIndex--; // change to the image to the left
else return; // do nothing

}
else if (recognizer.direction == UISwipeGestureRecognizerDirectionUp) {

if (self.currentImageIndex == 2 || self.currentImageIndex == 3) self.currentImageIndex -= 2; // change to the above image 
else return; // do nothing

}
else if (recognizer.direction == UISwipeGestureRecognizerDirectionDown) {

if (self.currentImageIndex == 0 || self.currentImageIndex == 1) self.currentImageIndex += 2; // change to the above image 
else return; // do nothing

}
[UIView animationWithDuration:0.5 animations:^{
    [self.imageView setAlpha:0];
} completion^(BOOL finished){
    if (finished) {
         [UIView animationWithDuration:0.5 animations:^{
             [self.imageView setImage[self.images objectAtIndex:self.currentImageIndex]];
             [self.imageView setAlpha:1];
         }];
    }
}];
}
于 2012-08-24T11:32:48.543 回答
0

要添加拖放功能，假设这就是您的意思，您需要查看UIPanGestureRecognizer

于 2012-08-24T10:54:15.993 回答