如何将UIActivityIndi​​catorView集中在UICollectionViewCell中？

Question

我试图在下载其图像时在每个集合视图单元格中放置一个UIActivityIndi​​catorView.我把它出现在每个细胞中,但它拒绝自我中心.它停留在左上角.我怎样才能让它正确居中？

我是这样做的:

extension UIView {

    func showActivityIndicator(onView: UIView, withIndicator: UIActivityIndicatorView) {
        withIndicator.frame = CGRect(x: onView.frame.midX - 20, y: onView.frame.midY - 20, width: 40, height: 40)
        withIndicator.activityIndicatorViewStyle = .whiteLarge
        withIndicator.center = onView.center
        onView.addSubview(withIndicator)
        withIndicator.startAnimating()
    }
}

我在cellForItemAtIndexPath中调用该函数,如:

showActivityIndicator(onView: cell.contentView, withIndicator: activityInd)

但我所做的一切都不会从左上角移动它.有什么建议？

Answer 1

试试这个

withIndicator.center = CGPointMake(self.frame.size.width/2, self.frame.size.height/2);