scrollToItem出错

原本我是这样写的

// 滚动到指定位置
DispatchQueue.main.async { [weak self] in
　　let indexPath = IndexPath(row: self!.currentNumber - 1, section: 0)
　　self!.collectionView.scrollToItem(at: indexPath, at: .left, animated: true)
}

发现问题，UICollectionView在iOS14上滚动不到指定indexPath，而在iOS14以下是正常的，莫名其妙

解决方法，添加UICollectionView公开扩展方法，计算滚动偏移量

public extension UICollectionView {
    func scrollTo(indexPath: IndexPath, animated: Bool = true) {
        let attributes = collectionViewLayout.layoutAttributesForItem(at: indexPath)!
        setContentOffset(attributes.frame.origin, animated: animated)
    }
}

修改后的代码

// 初始滚动到指定位置

DispatchQueue.main.async { [weak self] in
　　let indexPath = IndexPath(row: self!.currentNumber - 1, section: 0)
　　self!.collectionView.scrollTo(indexPath: indexPath)
}