我需要在UILabel中实现显示更多/显示更少，例如facebook。我的标签具有提及和网址功能。当文字中没有表情符号时，一切工作正常。我通过计算textHeight和标签的可见文本在标签的末尾添加了结尾。
这是我的扩展名文件
//
// extension.swift
// SeeMore
//
// Created by Macbook Pro on 14/10/20.
//
import Foundation
import UIKit
//MARK : - text height, weidth
extension Range where Bound == String.Index {
var nsRange:NSRange {
return NSRange(location: self.lowerBound.encodedOffset,
length: self.upperBound.encodedOffset -
self.lowerBound.encodedOffset)
}
}
extension String {
var extractURLs: [URL] {
var urls : [URL] = []
var error: NSError?
let detector = try? NSDataDetector(types: NSTextCheckingResult.CheckingType.link.rawValue)
var text = self
detector!.enumerateMatches(in: text, options: [], range: NSMakeRange(0, text.count), using: { (result: NSTextCheckingResult!, flags: NSRegularExpression.MatchingFlags, stop: UnsafeMutablePointer<ObjCBool>) -> Void in
// println("\(result)")
print("Extracted Result: \(result.url)")
urls.append(result.url!)
})
return urls
}
func textHeight(withConstrainedWidth width: CGFloat, font: UIFont) -> CGFloat {
let constraintRect = CGSize(width: width, height: .greatestFiniteMagnitude)
let boundingBox = self.boundingRect(with: constraintRect, options: [.usesLineFragmentOrigin, .usesFontLeading], attributes: [NSAttributedString.Key.font: font], context: nil)
return boundingBox.height
}
func textWidth(withConstrainedHeight height: CGFloat, font: UIFont) -> CGFloat {
let constraintRect = CGSize(width: .greatestFiniteMagnitude, height: height)
let boundingBox = self.boundingRect(with: constraintRect, options: .usesLineFragmentOrigin, attributes: [NSAttributedString.Key.font: font], context: nil)
return boundingBox.width
}
}
extension UILabel{
func indexOfAttributedTextCharacterAtPoint(point: CGPoint, font : UIFont) -> Int {
guard let attributedString = self.attributedText else { return -1 }
let mutableAttribString = NSMutableAttributedString(attributedString: attributedString)
// Add font so the correct range is returned for multi-line labels
mutableAttribString.addAttributes([NSAttributedString.Key.font: font], range: NSRange(location: 0, length: attributedString.length))
let textStorage = NSTextStorage(attributedString: mutableAttribString)
let layoutManager = NSLayoutManager()
textStorage.addLayoutManager(layoutManager)
let textContainer = NSTextContainer(size: frame.size)
textContainer.lineFragmentPadding = 0
textContainer.maximumNumberOfLines = numberOfLines
textContainer.lineBreakMode = lineBreakMode
layoutManager.addTextContainer(textContainer)
let index = layoutManager.characterIndex(for: point, in: textContainer, fractionOfDistanceBetweenInsertionPoints: nil)
return index
}
func addTrailingForShowLess(with trailingText: String, moreText: String, moreTextFont: UIFont, moreTextColor: UIColor, complition: @escaping (_ attribute: NSMutableAttributedString) -> Void) {
let readMoreText: String = trailingText + moreText
if let myText = self.text {
let trimmedString: String? = myText + trailingText
let readMoreLength: Int = (readMoreText.count)
guard let safeTrimmedString = trimmedString else { return }
if safeTrimmedString.count <= readMoreLength { return }
print("less this number \(safeTrimmedString.count) should never be less\n")
print("less then this number \(readMoreLength)")
// "safeTrimmedString.count - readMoreLength" should never be less then the readMoreLength because it'll be a negative value and will crash
// let trimmedForReadMore: String = (safeTrimmedString as NSString).replacingCharacters(in: NSRange(location: safeTrimmedString.count, length: readMoreLength), with: "") + trailingText
let answerAttributed = NSMutableAttributedString(string: safeTrimmedString, attributes: [NSAttributedString.Key.font: moreTextFont])
let readMoreAttributed = NSMutableAttributedString(string: moreText, attributes: [NSAttributedString.Key.font: moreTextFont, NSAttributedString.Key.foregroundColor: moreTextColor])
answerAttributed.append(readMoreAttributed)
complition(answerAttributed)
// self.attributedText = answerAttributed
}
}
func addTrailing(with trailingText: String, moreText: String, moreTextFont: UIFont, moreTextColor: UIColor, complition: @escaping (_ attribute: NSMutableAttributedString) -> Void) {
let readMoreText: String = trailingText + moreText
if self.text?.count == 0 { return }
if self.visibleTextLength == 0 { return }
let lengthForVisibleString: Int = self.visibleTextLength
if let myText = self.text {
let mutableString: String = myText
let trimmedString: String? = (mutableString as NSString).replacingCharacters(in: NSRange(location: lengthForVisibleString, length: myText.count - lengthForVisibleString), with: "")
let readMoreLength: Int = (readMoreText.count + 2)
guard let safeTrimmedString = trimmedString else { return }
if safeTrimmedString.count <= readMoreLength { return }
print("this number \(safeTrimmedString.count) should never be less\n")
print("then this number \(readMoreLength)")
// "safeTrimmedString.count - readMoreLength" should never be less then the readMoreLength because it'll be a negative value and will crash
let trimmedForReadMore: String = (safeTrimmedString as NSString).replacingCharacters(in: NSRange(location: safeTrimmedString.count - readMoreLength, length: readMoreLength), with: "") + trailingText
let answerAttributed = NSMutableAttributedString(string: trimmedForReadMore, attributes: [NSAttributedString.Key.font: moreTextFont])
let readMoreAttributed = NSMutableAttributedString(string: moreText, attributes: [NSAttributedString.Key.font: moreTextFont, NSAttributedString.Key.foregroundColor: moreTextColor])
answerAttributed.append(readMoreAttributed)
complition(answerAttributed)
// self.attributedText = answerAttributed
}
}
var visibleTextLength: Int {
let font: UIFont = self.font
let mode: NSLineBreakMode = self.lineBreakMode
let screenSize = UIScreen.main.bounds
let labelWidth: CGFloat = self.frame.size.width
let labelHeight: CGFloat = self.frame.size.height
let sizeConstraint = CGSize(width: labelWidth, height: CGFloat.greatestFiniteMagnitude)
if let myText = self.text {
let attributes: [AnyHashable: Any] = [NSAttributedString.Key.font: font]
let attributedText = NSAttributedString(string: myText, attributes: attributes as? [NSAttributedString.Key : Any])
let boundingRect: CGRect = attributedText.boundingRect(with: sizeConstraint, options: .usesLineFragmentOrigin, context: nil)
if boundingRect.size.height > labelHeight {
var index: Int = 0
var prev: Int = 0
let characterSet = CharacterSet.whitespacesAndNewlines
repeat {
prev = index
if mode == NSLineBreakMode.byCharWrapping {
index += 1
} else {
index = (myText as NSString).rangeOfCharacter(from: characterSet, options: [], range: NSRange(location: index + 1, length: myText.count - index - 1)).location
}
} while index != NSNotFound && index < myText.count && (myText as NSString).substring(to: index).boundingRect(with: sizeConstraint, options: .usesLineFragmentOrigin, attributes: attributes as? [NSAttributedString.Key : Any], context: nil).size.height <= labelHeight
return prev
}
}
if self.text == nil {
return 0
} else {
return self.text!.count
}
}
}
这是我的tableView单元格
//
// PostTableViewCell.swift
// SeeMore
//
// Created by Macbook Pro on 14/10/20.
//
import UIKit
protocol PostTableViewCellDelegate {
func postLabelAction(cell: PostTableViewCell, post: Post, tap: UITapGestureRecognizer)
}
class PostTableViewCell: UITableViewCell {
@IBOutlet weak var postLabel: UILabel!
var currentPost : Post?
var delegate: PostTableViewCellDelegate?
override func awakeFromNib() {
super.awakeFromNib()
postLabel.textColor = .black
let tapGesture = UITapGestureRecognizer(target: self, action: #selector(postLabelSelected))
tapGesture.numberOfTapsRequired = 1
postLabel.isUserInteractionEnabled = true
postLabel.addGestureRecognizer(tapGesture)
}
override func setSelected(_ selected: Bool, animated: Bool) {
super.setSelected(selected, animated: animated)
// Configure the view for the selected state
}
@objc func postLabelSelected(tap: UITapGestureRecognizer) {
delegate?.postLabelAction(cell: self, post: currentPost!, tap: tap)
}
func applyAttributedStringToPost(attributedString: NSMutableAttributedString, item: Post) {
let text = attributedString.string
let urls = text.extractURLs
for url in urls {
let range1 = (text as NSString).range(of: url.absoluteString)
attributedString.addAttribute(NSAttributedString.Key.foregroundColor, value: UIColor.blue, range: range1)
postLabel.attributedText = attributedString
}
postLabel.attributedText = attributedString
}
func setupItems(item : Post){
currentPost = item
let postText = item.postText
postLabel.numberOfLines = item.isExpendable ? 0 : 4
postLabel.text = postText
let underlineAttriString = NSMutableAttributedString(string: postText)
let urls = postText.extractURLs
for url in urls {
let range1 = (postText as NSString).range(of: url.absoluteString)
underlineAttriString.addAttribute(NSAttributedString.Key.foregroundColor, value: UIColor.blue, range: range1)
postLabel.attributedText = underlineAttriString
}
//Apply See more see less
postLabel.sizeToFit()
// let screenSize = UIScreen.main.bounds/
if let newfont = postLabel.font {
let textHeight = postText.textHeight(withConstrainedWidth: postLabel.frame.size.height, font: newfont)
if item.isExpendable {
postLabel.addTrailingForShowLess(with: "...", moreText: "Show Less", moreTextFont: newfont, moreTextColor: UIColor.blue) { (attributedString) in
self.applyAttributedStringToPost(attributedString: attributedString, item: item)
}
} else if postLabel.frame.size.height < textHeight, !item.isExpendable {
postLabel.addTrailing(with: "...", moreText: "Show More", moreTextFont: newfont, moreTextColor: UIColor.blue) { (attributedString) in
self.applyAttributedStringToPost(attributedString: attributedString, item: item)
}
}
}
}
}
这是我的视图控制器
// ViewController.swift
// SeeMore
//
// Created by Macbook Pro on 14/10/20.
//
import UIKit
struct Post {
var postText = ""
var isExpendable = false
}
class ViewController: UIViewController {
var postArray : [Post] = [Post]()
@IBOutlet weak var postTableView: UITableView!{
didSet{
settingUpTableView()
}
}
override func viewDidLoad() {
super.viewDidLoad()
fillUpPostData()
postTableView.reloadData()
}
func settingUpTableView() {
let nib = UINib(nibName: "PostTableViewCell", bundle: nil)
postTableView.register(nib, forCellReuseIdentifier: "PostTableViewCell")
postTableView.rowHeight = UITableView.automaticDimension
postTableView.estimatedRowHeight = 300
postTableView.separatorStyle = .singleLine
postTableView.separatorInset = .zero
}
func fillUpPostData() {
postArray.append(Post(postText: "Next, we established questions. We used❓liberally to indicate questions, and ? to indicate “I’m not understanding.” I’d say questions composed about 30–40% of our communication, so this was a critical emoji discovery.\nThen, we added more interesting complex relationships. ? implied that, after time, one thing would lead to another. ???️ means that “I’ll be able to talk soon.” We created a scale for asking “How do you feel?”: ????☹️?❓\nAs our communication advanced, we adopted each others’ language. My friend used ? to indicate “and.” After I understood, I started adopting the same emoji meaning. Since communication was so challenging and time-intensive, cooperating on each others’ emoji meaning was critical.\nTime in emoji is very expressive. ???????????????????????? allowed us to communicate time very easily", isExpendable: false))
postArray.append(Post(postText: "Apple has just finished its “Hi, Speed” event, where it finally took the wraps off the four new iPhone 12 phones, which have all-new designs and will all support 5G wireless networks. Apple also unveiled the HomePod mini, a smaller and more affordable version of the HomePod smart speaker.\nIf you want to read the play-by-play of the event, check out our live blog with commentary from Dieter Bohn and Nilay Patel. But if you just want to read the biggest news from the show, we’ve got you covered right here.\nApple has just finished its “Hi, Speed” event, where it finally took the wraps off the four new iPhone 12 phones, which have all-new designs and will all support 5G wireless networks. Apple also unveiled the HomePod mini, a smaller and more affordable version of the HomePod smart speaker.\nIf you want to read the play-by-play of the event, check out our live blog with commentary from Dieter Bohn and Nilay Patel. But if you just want to read the biggest news from the show, we’ve got you covered right here....Show Less", isExpendable: false))
postArray.append(Post(postText: "Next, we established questions. We used❓liberally to indicate questions, and ? to indicate \"I’m not understanding.\" I’d say questions composed about 30–40% of our communication, so this was a critical emoji discovery.\nThen, we added more interesting complex relationships. ? implied that, after time, one thing would lead to another. ???️ means that \"I’ll be able to talk soon.\" We created a scale for asking “How do you feel?\": ????☹️?❓\nAs our communication advanced, we adopted each others’ language. My friend used ? to indicate \"and.", isExpendable: false))
postArray.append(Post(postText: "BIG breaking news! Trump is going to have a fit over this one. “A former Department of Homeland Security official questioned in a scathing op-ed how anyone could vote for President Donald Trump in the 2020 election, citing the chaos that has characterized his administration and his mishandling of the coronavirus pandemic.\nElizabeth Neumann explained in a USA Today column ??????????????????????????❤️??☦️?????? published Tuesday why she is “convinced” the president is “failing at keeping Americans safe.” Neumann, until April, spent three years as a high-ranking member of the Trump administration’s national security team.\n“He is dangerous for our country,” she wrote.\nNeumann cited the president’s failure to address the surge in white nationalist violence, his constant lying and the turnover of key administration officials. Without elaborating, she also referred to what she said was a close call that could have led the U.S. into war.\n\nShe warned the country’s abandonment of allies and appeasement of dictators would “only get worse” in a second Trump term. Her column is headlined: “Trump made it hard for me to protect America. How could I vote for him again? How could anyone?”\n\nNeumann, ??????????????????????????❤️??☦️?????? who endorsed Democratic nominee Joe Biden in a video released by the Republican Voters Against Trump group in August, had particularly harsh commentary on the pandemic.\n\nTrump’s intentional public dismissal of the threat of COVID-19 — while acknowledging its “deadly” nature in private — was worse than a “dereliction of duty,” said Neumann.\n\n“Your government is supposed to perform some basic functions; keeping you and your family safe is primary among them,” she wrote. “In 2016, I voted for President Trump. But when someone asked me if I could vote for him again, after he time and again refused to keep Americans safe — how could I say anything but no? How could anyone?” ", isExpendable: false))
postArray.append(Post(postText: " \n\n\nHere is her entire op-Ed: Everything we saw during the first presidential debate is indicative of how President Donald Trump behaves in the White House. His business model is chaos. ??????????????????????????❤️??☦️??????He has no organization, no leadership, and sees every interaction as a contest or a battle, even when it doesn’t have to be. Chris Wallace now knows how so many administration staffers feel — and how I felt when the president got in the way of me doing my job. He is dangerous for our country.\n\nI served as the Assistant Secretary of Homeland Security for Counterterrorism and Threat Prevention, and my job was to help keep Americans safe from terrorist attacks. My time in office coincided with a dramatic rise in white nationalist violence, but my colleagues and I couldn’t get the president to help address the problem. At the debate, America saw what I saw in the administration: President Trump refuses to distance himself from white nationalists. ??????????????????????????❤️??☦️??????I realized after watching the White House response to the terrorist attack in El Paso that his rhetoric was a recruitment tool for violent extremist groups. The president bears some responsibility for the deaths of Americans at the hands of these violent extremists.\n\n\nAs a conservative, I believe a primary purpose of the federal government is to provide for the national defense. Under the Constitution, it is a mandatory function of the federal government. After serving for three years inside the Trump administration’s national security team, I am convinced the president is failing at keeping Americans safe.\n\nEarly on in the administration, I represented the Department of Homeland Security at several meetings in which a White House staff member implied that the president had approved, and that we should begin to carry out, plans that could have led the United States into war. Thankfully, there were experienced people in the room who had enough clout to suggest that these catastrophic plans needed a second look. Many of us weren’t sure what, if anything, the president had actually approved, or that he had been properly briefed to ensure he understood the risks involved. These people helped us avoid war.", isExpendable: false))
postArray.append(Post(postText: "\n\nHaving adults in the room matters. They protect the country from a chaotic White House structure that allows staffers to run amok. But more importantly, they ensure that the president is presented with unvarnished truth, that difficult topics like domestic terrorism are raised even when he ??????????????????????????❤️??☦️??????doesn’t want to acknowledge them.\n\nEvery day, the number of experienced people in the administration that have the ability to speak truth to power shrinks. We are seeing the results: abandoning our allies and cozying up to dictators, emboldening our enemies and weakening our standing in the world. This would only get worse in a second Trump term.\n\nJust as he ignored white nationalists, he also ignored COVID-19. After nearly 20 years around national crises, you can recognize a good response — and a bad one. By late January, professionals and outside experts were sounding the alarms. Health and Human Services Secretary Alex Azar declared a public health emergency on Jan. 31. But throughout February, longtime colleagues at the Federal ??????????????????????????❤️??☦️??????Emergency Management Agency were privately expressing dismay at the flailing response.\n\nBob Woodward’s revelations last month, using the president’s own words, demonstrate that the government’s failure wasn’t just because of bureaucracy, the newness of the virus, or even the president sticking his head in the sand. It was intentional. This is worse than dereliction of duty — this is willfully leading defenseless people to a killer. President Trump repeatedly lied to the American public. Those lies have led to more deaths and illnesses.\n\nA recent study assessed that had we exercised our pandemic mitigation plans (which have existed since 2005), as other wealthy countries did, nearly 9 million more Americans would be employed, and over 100,000 would still be alive. We could have saved half of the Americans who have died so far.\n\nYour government is supposed to perform some basic functions; keeping you and your family safe is primary among them. In 2016, I voted for President Trump. But when someone asked me if I could vote for him again, after he time and again refused to keep Americans safe — how could I say anything but no? How could anyone?...Show Less", isExpendable: false))
postArray.append(Post(postText: "\nPamela Lindsay:\n”just another conspiracy theory that proved to be untrue look at all the money he has wasted for something that was patently untrue. how many does this make that he yelled about some half baked ??????????????????????????❤️??☦️??????conspiracy theory that just showed how desperate he is. yet look at the number that will still follow him he and they are truly deplorable.\nBeverly Jones: ”Tax dollars wasted in another attempt to blame a former President of wrong-doing. Since we already know #45's wrongdoings, an investigation will cost nothing.", isExpendable: false))
postArray.append(Post(postText: "Judy Stamberger:\n \"AN incredible, 8 yrs served with dignity, kindness, no lawsuits, arrests, no impeachment, no crude remarks, respectful man & his family.\"\nJames S Lechleitnerjr:\n\"Outstanding men Martin Luther King, and President Barack Obama...\nAmen❗️??????????????????????????❤️??☦️??????‼️\"\nCarol Brown-Hatcher:\n\"Greatness, Grace, Integrity, Honorable(Men,) Brilliant, Humble, Brave, Courageous. THEY WOULD NOT BE SILENCED. They knew the meaning of \"Responsibility\".", isExpendable: false))
postArray.append(Post(postText: "BRAVO! ? We love this!!! A North Dakota farmer is going viral for plowing a pro-Biden-Harris message into his field. Peter Larson says that this is the first time he has used his fields to share his political views. He hopes to encourage others to get out and vote. Great idea, Peter! ??? Follow Ridin' With Biden to defeat Trump and save America! ??????...Show Less", isExpendable: false))
postArray.append(Post(postText: "Ridin' With Biden:\n\"Olivia Troye, who until a couple of months ago was on Mike Pence's FAILED Coronavirus \"Response\" Task Force, just slammed Trump for PRETENDING that Dr. Fauci praised Trump's disastrous COVID response in a misleading campaign ad. Follow Ridin' With Biden to defeat Trump and save America!\" ??????", isExpendable: false))
}
}
extension ViewController: UITableViewDelegate, UITableViewDataSource{
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return postArray.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "PostTableViewCell", for: indexPath) as! PostTableViewCell
cell.setupItems(item: postArray[indexPath.row])
cell.delegate = self
return cell
}
}
extension ViewController: PostTableViewCellDelegate{
func postLabelAction(cell: PostTableViewCell,post: Post, tap: UITapGestureRecognizer) {
let tapLocation = tap.location(in: cell.postLabel)
let tapIndex = cell.postLabel.indexOfAttributedTextCharacterAtPoint(point: tapLocation, font: cell.postLabel.font!)
var rangeArray: [NSRange] = [NSRange]()
var linkRangeArray: [NSRange] = [NSRange]()
let postText = cell.postLabel.text
var seemoreText = ""
seemoreText = post.isExpendable ? "Show Less" : "Show More"
//
if let seeRange = postText?.range(of: seemoreText)?.nsRange {
if tapIndex > seeRange.location && tapIndex < seeRange.location + seeRange.length {
if let indexPath = postTableView.indexPath(for: cell) {
let isExpanded = self.postArray[indexPath.row].isExpendable
self.postArray[indexPath.row].isExpendable = !isExpanded
DispatchQueue.main.async { [weak self] in
self?.postTableView.reloadRows(at: [indexPath], with: .automatic)
self?.postTableView.scrollToRow(at: indexPath, at: .top, animated: true)
}
return
}
}
}
if let urls = postText?.extractURLs {
for url in urls {
guard let range = postText?.range(of: url.absoluteString)?.nsRange else { return }
linkRangeArray.append(range)
}
for (index, neRange) in linkRangeArray.enumerated() {
if tapIndex > neRange.location && tapIndex < neRange.location + neRange.length {
print("link print")
let vc = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "LinkPreviewWebViewController") as! LinkPreviewWebViewController
vc.loadURL = urls[index].absoluteString
self.navigationController?.isNavigationBarHidden = false
self.navigationController?.pushViewController(vc, animated: true)
return
}
}
}
// mention logic will be there
}
}
如果在张贴文字visibleTextLength之前有表情符号或多余的行距，则返回错误的计数，因此用户看不到显示更多文字，因为该文字位于可见文字下方。甚至label.frame.size也无法提供不同设备的当前宽度。任何帮助将不胜感激。 TIA
[请忽略发自真实用户的帖子文字，以产生问题] 应该提到的是，我已经尝试了Expendable Label和ReadMoreTextView，但它们不能很好地为我服务。
答案 0 :(得分：-1)
您可以使用https://github.com/apploft/ExpandableLabel此类在UILabel中显示更多/阅读更多/更多功能。此类可根据您的要求进行定制。我用它可以正常工作。
我希望它对您有用。 谢谢。
