问题描述
如何用 Swift 写这个?
更新:发布了我试图转换的方法,最初发布了一个不同的方法,这不是我试图隐藏的
Update: posted the method I'm trying to convert, originally posted a different method that was not what I was trying to covert
这适用于 Objective C,但不适用于 Swift.当我尝试将 ceilf
和 floorf
与 CGFloat
一起使用时,出现转换错误.
This works in Objective C, but not Swift. I get conversion errors when I try to use ceilf
and floorf
with CGFloat
.
- (void)scrollViewWillEndDragging:(UIScrollView *)scrollView withVelocity:(CGPoint)velocity targetContentOffset:(inout CGPoint *)targetContentOffset
{
float pageWidth = 200 + 30; // width + space
float currentOffset = scrollView.contentOffset.x;
float targetOffset = targetContentOffset->x;
float newTargetOffset = 0;
if (targetOffset > currentOffset)
newTargetOffset = ceilf(currentOffset / pageWidth) * pageWidth;
else
newTargetOffset = floorf(currentOffset / pageWidth) * pageWidth;
if (newTargetOffset < 0)
newTargetOffset = 0;
else if (newTargetOffset > scrollView.contentSize.width)
newTargetOffset = scrollView.contentSize.width;
targetContentOffset->x = currentOffset;
[scrollView setContentOffset:CGPointMake(newTargetOffset, 0) animated:YES];
}
推荐答案
Christian 的回答:我能够用 Swift 重写它.我将所有东西都设置为 Float
来做数学运算,然后像 Christian 提到的那样转换为 CGFloat
是可能的.他的回答在技术上是正确的,但向新的 iOS 开发人员展示是如何用 Swift 编写正是我想要的.
To answer from Christian: I was able to rewrite this in Swift. I set everything up as Float
to do the math then converted to CGFloat
as Christian mentioned was possible. His answer is technically correct, but showing a newer iOS developer how this is written in Swift was what I was looking for.
func scrollViewWillEndDragging(scrollView: UIScrollView!, withVelocity velocity: CGPoint, targetContentOffset: UnsafePointer<CGPoint>) {
var pageWidth = Float(200 + 30)
var currentOffset = Float(scrollView.contentOffset.x)
var targetOffset = Float(targetContentOffset.memory.x)
var newTargetOffset = Float(0)
var scrollViewWidth = Float(scrollView.contentSize.width)
if targetOffset > currentOffset {
newTargetOffset = ceilf(currentOffset / pageWidth) * pageWidth
} else {
newTargetOffset = floorf(currentOffset / pageWidth) * pageWidth
}
if newTargetOffset < 0 {
newTargetOffset = 0
} else if newTargetOffset > currentOffset {
newTargetOffset = currentOffset
}
Float(targetContentOffset.memory.x) == currentOffset
scrollView.setContentOffset(CGPointMake(CGFloat(newTargetOffset), 0), animated: true)
}
这篇关于在 Swift 中,您将如何编写 scrollViewWillEndDragging withVelocity targetContentOffset 方法?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!