問(wèn)題描述

我在 UIScrollView 中有一個(gè)非滾動(dòng) UITableView.我將 UITableView 的幀大小設(shè)置為其內(nèi)容大小.

I have a non scrolling UITableView in a UIScrollView. I set the frame size of the UITableView to its content size.

當(dāng)我向 UITableView 添加一行時(shí)，我在 UITableView 上調(diào)用 insertRowsAtIndexPaths:withRowAnimation:.然后我調(diào)用一個(gè)方法來(lái)調(diào)整 UITableView 的框架:

When I add a row to the UITableView, I call insertRowsAtIndexPaths:withRowAnimation: on the UITableView. Then I call a method to resize the frame of the UITableView:

- (void)resizeTableViewFrameHeight
{
    // Table view does not scroll, so its frame height should be equal to its contentSize height
    CGRect frame = self.tableView.frame;
    frame.size = self.tableView.contentSize;
    self.tableView.frame = frame;
}

目前看來(lái)，contentSize 尚未更新.如果我在上述方法中根據(jù)行數(shù)和節(jié)數(shù)手動(dòng)計(jì)算框架，則該方法可以正常工作.

It seems though that the contentSize hasn't been updated at this point. If I manually calculate the frame in the above method based on the number of rows and sections, then the method works properly.

我的問(wèn)題是，如何讓 UITableView 更新其 contentSize?我想我可以調(diào)用 reloadData 并且可能會(huì)這樣做，但是當(dāng)我只插入一個(gè)單元格時(shí)重新加載整個(gè)表格似乎效率低下.

My question is, how can I get the UITableView to update its contentSize? I suppose I could call reloadData and that would probably do it, but it seems inefficient to reload the entire table when I'm just inserting one cell.

推薦答案

在UITableView上調(diào)用layoutIfNeeded可以讓UITableView立即計(jì)算出內(nèi)容的大小.這將運(yùn)行所有必要的計(jì)算來(lái)布局 UITableView.

You can make the UITableView calculate the size of the content immediately by calling layoutIfNeeded on the UITableView. This will run all the necessary calculations to layout the UITableView.

UITableViewController 子類(lèi)示例，您希望將其放入可變大小的容器視圖中:

Example for a UITableViewController subclass that you want to put in a container view with variable size:

Objective-C

- (CGSize)preferredContentSize
{
    // Force the table view to calculate its height
    [self.tableView layoutIfNeeded];
    return self.tableView.contentSize;
}

斯威夫特

override var preferredContentSize: CGSize {
    get {
        // Force the table view to calculate its height
        self.tableView.layoutIfNeeded()
        return self.tableView.contentSize
    }
    set {}
}

這篇關(guān)于UITableView 的 contentSize 何時(shí)設(shè)置?的文章就介紹到這了，希望我們推薦的答案對(duì)大家有所幫助，也希望大家多多支持html5模板網(wǎng)！