Question

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，而不是对角交换。例如，第一张图像可以与其右侧和下方的图像交换，第二张图像只能与左侧和下方的图像交换，依此类推。任何人都可以帮我解决如何做到这一点。谢谢

Answer 1

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

Answer 2

添加滑动手势识别器。当用户滑动确定哪个方向并处理图像交换时。

[编辑] - 想象一个分为四个相等部分的正方形。左上部分的索引为零，右上角为索引1，左下角为索引2，最后右下角为索引3.下面的代码检查当前索引，并从中确定是否有图像可以进行交换，如果不是，它就什么都不做。

这段代码来自我的头脑，因此可能存在语法错误，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];
         }];
    }
}];
}

在IOS中交换图像

2 个答案: