滚动时如何在UIScrollView中向一个方向移动 [英] how to move one direction in UIScrollView when scrolling
问题描述
我是Objective-c的新手.我创建 UIScrollView 对象，并在此视图中添加以下代码:
I'm new in objective-c. I create UIScrollView object and add in my view with this code:
height = self.view.frame.size.height;
width = self.view.frame.size.width;
scrollbar = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 0, width, height)];
scrollbar.delegate = self;
scrollbar.backgroundColor = [UIColor whiteColor];
scrollbar.maximumZoomScale = 1.0;
scrollbar.minimumZoomScale = 1.0;
scrollbar.clipsToBounds = YES;
scrollbar.showsHorizontalScrollIndicator = YES;
scrollbar.pagingEnabled = YES;
[scrollbar setContentSize:CGSizeMake(width*4, height*4)];
[self.view addSubview:scrollbar];
for (int i = 1; i <= 4; i++) {
first = [[FirstViewController alloc]initWithNibName:@"FirstViewController" bundle:nil];
first.view.frame = CGRectMake((i-1)*width, 0, width, height*4);
[scrollbar addSubview:first.view];
switch (i) {
ase 1:
first.view.backgroundColor = [UIColor blueColor];
break;
case 2:
first.view.backgroundColor = [UIColor redColor];
break;
case 3:
first.view.backgroundColor = [UIColor greenColor];
break;
case 4:
first.view.backgroundColor = [UIColor grayColor];
break;
default:
break;
}
}
在我的代码中，当我在ScrollView上滚动检测dx&时，我现在想要在ScrollView中添加4种不同颜色的视图dy(dx:在Axis.x上的行驶距离，而dy:在Axis.y上的行驶距离)，并检查这两个变量以及何时:
in my code I add 4 view in my ScrollView with different color now I want when scrolling on my ScrollView detect dx & dy (dx: driving distance on Axis.x & dy:driving distance on Axis.y) and check these two variable and when :
Notic:我想当对ScrollView进行任何触摸并在Axis(x或y)上进行移动触摸或在Both Axis(x和y)上进行触摸时进行检查:
Notic: I want when any one touch on ScrollView and moving touch on Axis (x or y) or touch on Both Axis (x and y) check this :
如果(dx> dy)禁用水平滚动并沿垂直方向移动！！！否则在水平方向移动并禁用垂直滚动！！！
- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
CGRect visibleRect = CGRectMake(scrollView.contentOffset.x, scrollView.contentOffset.y, scrollView.contentOffset.x + scrollView.bounds.size.width, scrollView.contentOffset.y + scrollView.bounds.size.height);
NSLog(@"%f,%f",visibleRect.origin.x,visibleRect.origin.y);
/*NSLog(@"x : %f",scrollView.contentOffset.x);
NSLog(@"y : %f",scrollView.contentOffset.y);*/
if (fabsf(scrollView.contentOffset.x) > fabsf(scrollView.contentOffset.y)) {
NSLog(@"Vertical Side");
}
else {
NSLog(@"Horizontal Side");
}
}
请指导我.我不能禁用一侧并移动另一侧！！！谢谢
please guide me guys. I can't disable one side and move another side!!! thanks
推荐答案
您可以实现将一些代码添加到委托中的结果.这是我的 ViewController.m 文件. -viewDidLoad ， #import 语句和其他方法被省略.
You can achieve the result you want adding some code to your delegate. This is my ViewController.m file. -viewDidLoad, #import statements and the other methods are omitted.
@interface ViewController () {
CGPoint initialOffset;
NSInteger direction; // 0 undefined, 1 horizontal, 2 vertical
}
@end
@implementation ViewController
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
// retrieve current offset
CGPoint currentOffset = scrollView.contentOffset;
// do we know which is the predominant direction?
if (direction == 0) {
// no.
CGFloat dx = currentOffset.x - initialOffset.x;
CGFloat dy = currentOffset.y - initialOffset.y;
// we need to decide in which direction we are moving
if (fabs(dx) >= fabs(dy)) {
direction = 1; // horizontal
} else if (fabs(dy) > fabs(dx)) {
direction = 2;
}
}
// ok now we have the direction. update the offset if necessary
if (direction == 1 && currentOffset.y != initialOffset.y) {
// remove y offset
currentOffset.y = initialOffset.y;
// update
[scrollView setContentOffset:currentOffset];
} else if (direction == 2 && currentOffset.x != initialOffset.x) {
currentOffset.x = initialOffset.x;
[scrollView setContentOffset:currentOffset];
}
}
- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView
{
// store the current offset
initialOffset = scrollView.contentOffset;
// reset flag
direction = 0; // AKA undefined
}
@end
当您开始拖动时，委托将标志 direction 重置为未知"状态，并存储当前的内容偏移量.每次拖动后，您的 -scrollViewDidScroll:都会被调用.在那里，您可以确定哪个方向是主要方向(如果尚未完成)，然后通过删除x(或y)偏移量来相应地校正当前滚动偏移量.
When you start dragging, the delegate will reset the flag direction to "unknown" state, and store the current content offset. After every dragging move, your -scrollViewDidScroll: will be called. There, you decide which is the predominant direction (if this hasn't been done yet) and correct the current scrolling offset accordingly, by removing the x (or y) offset.
我使用您提供的相同设置对此进行了测试，只有在 UIScrollView 中使用了 UIImageView 并通过InterfaceBuilder进行了所有设置，但它应该可以正常工作.从理论上讲，使用此方法可以替换 directionLock ，但是请记住，在操作期间多次调用 -scrollViewDidScroll ，并且每次重写内容偏移量时(如果滚动是双向发生).因此，如果保留启用 directionLock 的功能，则可以将委托执行的许多调用保存到 setContentOffset:中.
I tested this with the same settings you provided, only I used a UIImageView inside UIScrollView and I set up everything via InterfaceBuilder, but it should work fine. Theoretically, with this method you could replace directionLock, but remember that -scrollViewDidScroll is called many times during an action, and every time it rewrites the content offset (if the scrolling is happening in both directions). So if you leave directionLock enabled, you save many of the calls to setContentOffset: that the delegate performs.
这篇关于滚动时如何在UIScrollView中向一个方向移动的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
