ios 动态设置 tableHeaderView 高度

Setting tableHeaderView height dynamically

提问by TravMatth

My application creates a UITableViewController that contains a custom tableHeaderView which may have an arbitrary height. I've been struggling with a way to set this header dynamically, as it seems the suggested ways have been cutting this header short. My UITableViewController's relevant code:

我的应用程序创建了一个 UITableViewController，其中包含一个自定义的 tableHeaderView，它可能具有任意高度。我一直在努力寻找一种动态设置此标题的方法，因为似乎建议的方法已缩短此标题。我的 UITableViewController 的相关代码：

import UIKit
import SafariServices

class RedditPostViewController: UITableViewController, NetworkCommunication, SubViewLaunchLinkManager {

    //MARK: UITableViewDataSource
    var post: PostData?
    var tree: CommentTree?
    weak var session: Session! = Session.sharedInstance

    override func viewDidLoad() {
        super.viewDidLoad()

        // Get post info from api
        guard let postData = post else { return }

        //Configure comment table
        self.tableView.registerClass(RedditPostCommentTableViewCell.self, forCellReuseIdentifier: "CommentCell")

       let tableHeader = PostView(withPost: postData, inViewController: self)
       let size = tableHeader.systemLayoutSizeFittingSize(UILayoutFittingExpandedSize)
       let height = size.height
       let width = size.width
       tableHeader.frame = CGRectMake(0, 0, width, height)
       self.tableView.tableHeaderView = tableHeader


       session.getRedditPost(postData) { (post) in
           self.post = post?.post
           self.tree = post?.comments
           self.tableView.reloadData()
       }
    }
}

This results in the following incorrect layout:

这会导致以下不正确的布局：

If I change the line: tableHeader.frame = CGRectMake(0, 0, width, height)to tableHeader.frame = CGRectMake(0, 0, width, 1000)the tableHeaderView will lay itself out correctly:

如果我更改行：tableHeader.frame = CGRectMake(0, 0, width, height)到tableHeader.frame = CGRectMake(0, 0, width, 1000)tableHeaderView 将正确布局：

I'm not sure what I'm doing incorrectly here. Also, custom UIView class, if this helps:

我不确定我在这里做错了什么。此外，自定义 UIView 类，如果这有帮助：

import UIKit
import Foundation

protocol SubViewLaunchLinkManager: class {
    func launchLink(sender: UIButton)
}

class PostView: UIView {

    var body: UILabel?
    var post: PostData?
    var domain: UILabel?
    var author: UILabel?
    var selfText: UILabel?
    var numComments: UILabel?

    required init?(coder aDecoder: NSCoder) {
        fatalError("Not implemented yet")
    }

    init(withPost post: PostData, inViewController viewController: SubViewLaunchLinkManager) {
        super.init(frame: CGRectZero)

        self.post = post
        self.backgroundColor = UIColor.lightGrayColor()

        let launchLink = UIButton()
        launchLink.setImage(UIImage(named: "circle-user-7"), forState: .Normal)
        launchLink.addTarget(viewController, action: "launchLink:", forControlEvents: .TouchUpInside)
        self.addSubview(launchLink)

        selfText = UILabel()
        selfText?.backgroundColor = UIColor.whiteColor()
        selfText?.numberOfLines = 0
        selfText?.lineBreakMode = .ByWordWrapping
        selfText!.text = post.selfText
        self.addSubview(selfText!)
        selfText?.sizeToFit()

        //let attributedString = NSAttributedString(string: "Test"/*post.selfTextHtml*/, attributes: [NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType])
        //selfText.attributedText = attributedString

        body = UILabel()
        body!.text = post.title
        body!.numberOfLines = 0
        body!.lineBreakMode = .ByWordWrapping
        body!.textAlignment = .Justified
        self.addSubview(body!)

        domain = UILabel()
        domain!.text = post.domain
        self.addSubview(domain!)

        author = UILabel()
        author!.text = post.author
        self.addSubview(author!)

        numComments = UILabel()
        numComments!.text = "\(post.numComments)"
        self.addSubview(numComments!)

        body!.translatesAutoresizingMaskIntoConstraints = false
        domain!.translatesAutoresizingMaskIntoConstraints = false
        author!.translatesAutoresizingMaskIntoConstraints = false
        selfText!.translatesAutoresizingMaskIntoConstraints = false
        launchLink.translatesAutoresizingMaskIntoConstraints = false
        numComments!.translatesAutoresizingMaskIntoConstraints = false

        let views: [String: UIView] = ["body": body!, "domain": domain!, "author": author!, "numComments": numComments!, "launchLink": launchLink, "selfText": selfText!]
        //let selfTextSize = selfText?.sizeThatFits((selfText?.frame.size)!)
        //print(selfTextSize)
        //let metrics = ["selfTextHeight": selfTextSize!.height]

                   self.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("V:|-[body]-[selfText]-[domain]-|", options: [], metrics: nil, views: views))
       self.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("V:|-[body]-[selfText]-[author]-|", options: [], metrics: nil, views: views))
    self.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("V:|-[body]-[selfText]-[numComments]-|", options: [], metrics: nil, views: views))
    self.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("V:|-[launchLink]-[numComments]-|", options: [], metrics: nil, views: views))
    self.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("H:|[body][launchLink]|", options: [], metrics: nil, views: views))
    self.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("H:|[selfText][launchLink]|", options: [], metrics: nil, views: views))
    self.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("H:|[domain][author][numComments][launchLink]|", options: [], metrics: nil, views: views))
}

override func layoutSubviews() {
    super.layoutSubviews()
    body?.preferredMaxLayoutWidth = body!.bounds.width
}
}

回答by TravMatth

Copied from this post. (Make sure you see it if you're looking for more details)

从这个帖子复制。（如果您正在寻找更多详细信息，请确保您看到它）

override func viewDidLayoutSubviews() {
    super.viewDidLayoutSubviews()

    if let headerView = tableView.tableHeaderView {

        let height = headerView.systemLayoutSizeFitting(UIView.layoutFittingCompressedSize).height
        var headerFrame = headerView.frame

        //Comparison necessary to avoid infinite loop
        if height != headerFrame.size.height {
            headerFrame.size.height = height
            headerView.frame = headerFrame
            tableView.tableHeaderView = headerView
        }
    }
}

回答by NSExceptional

Determining the header's frame size using

使用确定标题的帧大小

header.systemLayoutSizeFitting(UILayoutFittingCompressedSize)

as suggested in the answers above didn't work for me when my header view consisted of a single multiline label. With the label's line break mode set to wrap, the text just gets cut off:

当我的标题视图由单个多行标签组成时，如上述答案中所建议的那样对我不起作用。将标签的换行模式设置为换行，文本就会被截断：

Instead, what did work for me was using the width of the table view and a height of 0 as the target size:

相反，对我有用的是使用表格视图的宽度和 0 的高度作为目标大小：

header.systemLayoutSizeFitting(CGSize(width: tableView.bounds.width, height: 0))

Putting it all together (I prefer to use an extension):

将它们放在一起（我更喜欢使用扩展名）：

extension UITableView {
    func updateHeaderViewHeight() {
        if let header = self.tableHeaderView {
            let newSize = header.systemLayoutSizeFitting(CGSize(width: self.bounds.width, height: 0))
            header.frame.size.height = newSize.height
        }
    }
}

And call it like so:

并这样称呼它：

override func viewWillLayoutSubviews() {
    super.viewWillLayoutSubviews()
    tableView.updateHeaderViewHeight()
}

回答by Nathan Hosselton

More condensed version of OP's answer, with the benefit of allowing layout to happen naturally (note this solution uses viewWillLayoutSubviews):

OP 答案的更精简版本，其好处是允许布局自然发生（请注意，此解决方案使用视图WillLayoutSubviews）：

override func viewWillLayoutSubviews() {
    super.viewWillLayoutSubviews()

    if let header = tableView.tableHeaderView {
        let newSize = header.systemLayoutSizeFitting(UIView.layoutFittingCompressedSize)
        header.frame.size.height = newSize.height
    }
}

Thanks to TravMatth for the original answer.

感谢 TravMatth 的原始答案。

回答by emrekyv

If you're still having problems with layout with the above code sample, there's a slight chance you disabled translatesAutoresizingMaskIntoConstraintson the custom header view. In that case, you need to set translatesAutoresizingMaskIntoConstraintsback to trueafter you set the header's frame.

如果您在使用上述代码示例时仍然遇到布局问题，则您可能会禁用translatesAutoresizingMaskIntoConstraints自定义标题视图。在这种情况下，您需要在设置标题的框架后translatesAutoresizingMaskIntoConstraints重新true设置。

Here's the code sample I'm using, and working correctly on iOS 11.

这是我正在使用的代码示例，并且可以在 iOS 11 上正常运行。

public override func viewDidLayoutSubviews() {
    super.viewDidLayoutSubviews()

    guard let headerView = tableView.tableHeaderView else { return }

    let height = headerView.systemLayoutSizeFitting(UILayoutFittingCompressedSize).height
    var headerFrame = headerView.frame

    if height != headerFrame.size.height {
        headerFrame.size.height = height
        headerView.frame = headerFrame
        tableView.tableHeaderView = headerView

        if #available(iOS 9.0, *) {
            tableView.layoutIfNeeded()
        }
    }

    headerView.translatesAutoresizingMaskIntoConstraints = true
}

回答by Khoren Asatryan

override func viewDidLayoutSubviews() {
        super.viewDidLayoutSubviews()
        if let headerView = self.tableView.tableHeaderView {
            let headerViewFrame = headerView.frame
            let height = headerView.systemLayoutSizeFitting(headerViewFrame.size, withHorizontalFittingPriority: UILayoutPriority.defaultHigh, verticalFittingPriority: UILayoutPriority.defaultLow).height
            var headerFrame = headerView.frame
            if height != headerFrame.size.height {
                headerFrame.size.height = height
                headerView.frame = headerFrame
                self.tableView.tableHeaderView = headerView
            }
        }
    }

Problem in calculating label size when using horizontal or vertical fitting

使用水平或垂直拟合时计算标签大小的问题

回答by Gurpreet Singh

**My Working Solution is:
Add this function in viewcontroller**
public override func viewDidLayoutSubviews() {
        super.viewDidLayoutSubviews()
        guard let headerView = myTableView.tableHeaderView else { return }
        let height = headerView.systemLayoutSizeFitting(UILayoutFittingCompressedSize).height
        var headerFrame = headerView.frame

        if height != headerFrame.size.height {
            headerFrame.size.height = height
            headerView.frame = headerFrame
            myTableView.tableHeaderView = headerView

            if #available(iOS 9.0, *) {
                myTableView.layoutIfNeeded()
            }
        }

        headerView.translatesAutoresizingMaskIntoConstraints = true
} 


 **Add one line in header's view class.**
override func layoutSubviews() {
        super.layoutSubviews()
        bookingLabel.preferredMaxLayoutWidth = bookingLabel.bounds.width

    }

回答by kachulach

Just implementing these two UITableView delegate methods worked for me:

只是实现这两个 UITableView 委托方法对我有用：

-(CGFloat)tableView:(UITableView *)tableView estimatedHeightForHeaderInSection:(NSInteger)section
{
    return 100;
}

-(CGFloat)tableView:(UITableView *)tableView heightForHeaderInSection:(NSInteger)section
{
    return UITableViewAutomaticDimension;
}