许多应用程序都有文本,文本中是圆角矩形的web超链接,当我点击它们时,UIWebView就会打开。让我困惑的是,他们经常有自定义链接,例如,如果单词以#开头,它也是可点击的,应用程序通过打开另一个视图来响应。我该怎么做呢?是否可以用UILabel或者我需要UITextView或者其他什么?
当前回答
这是一个Objective-C类别,它支持现有UILabel中的可点击链接。attributedText字符串,利用现有的NSLinkAttributeName属性。
@interface UILabel (GSBClickableLinks) <UIGestureRecognizerDelegate>
@property BOOL enableLinks;
@end
#import <objc/runtime.h>
static const void *INDEX;
static const void *TAP;
@implementation UILabel (GSBClickableLinks)
- (void)setEnableLinks:(BOOL)enableLinks
{
UITapGestureRecognizer *tap = objc_getAssociatedObject(self, &TAP); // retreive tap
if (enableLinks && !tap) { // add a gestureRegonzier to the UILabel to detect taps
tap = [UITapGestureRecognizer.alloc initWithTarget:self action:@selector(openLink)];
tap.delegate = self;
[self addGestureRecognizer:tap];
objc_setAssociatedObject(self, &TAP, tap, OBJC_ASSOCIATION_RETAIN_NONATOMIC); // save tap
}
self.userInteractionEnabled = enableLinks; // note - when false UILAbel wont receive taps, hence disable links
}
- (BOOL)enableLinks
{
return (BOOL)objc_getAssociatedObject(self, &TAP); // ie tap != nil
}
// First check whether user tapped on a link within the attributedText of the label.
// If so, then the our label's gestureRecogizer will subsequently fire, and open the corresponding NSLinkAttributeName.
// If not, then the tap will get passed along, eg to the enclosing UITableViewCell...
// Note: save which character in the attributedText was clicked so that we dont have to redo everything again in openLink.
- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer
{
if (gestureRecognizer != objc_getAssociatedObject(self, &TAP)) return YES; // dont block other gestures (eg swipe)
// Re-layout the attributedText to find out what was tapped
NSTextContainer *textContainer = [NSTextContainer.alloc initWithSize:self.frame.size];
textContainer.lineFragmentPadding = 0;
textContainer.maximumNumberOfLines = self.numberOfLines;
textContainer.lineBreakMode = self.lineBreakMode;
NSLayoutManager *layoutManager = NSLayoutManager.new;
[layoutManager addTextContainer:textContainer];
NSTextStorage *textStorage = [NSTextStorage.alloc initWithAttributedString:self.attributedText];
[textStorage addLayoutManager:layoutManager];
NSUInteger index = [layoutManager characterIndexForPoint:[gestureRecognizer locationInView:self]
inTextContainer:textContainer
fractionOfDistanceBetweenInsertionPoints:NULL];
objc_setAssociatedObject(self, &INDEX, @(index), OBJC_ASSOCIATION_RETAIN_NONATOMIC); // save index
return (BOOL)[self.attributedText attribute:NSLinkAttributeName atIndex:index effectiveRange:NULL]; // tapped on part of a link?
}
- (void)openLink
{
NSUInteger index = [objc_getAssociatedObject(self, &INDEX) unsignedIntegerValue]; // retrieve index
NSURL *url = [self.attributedText attribute:NSLinkAttributeName atIndex:index effectiveRange:NULL];
if (url && [UIApplication.sharedApplication canOpenURL:url]) [UIApplication.sharedApplication openURL:url];
}
@end
这将通过一个UILabel子类(即没有objc_getAssociatedObject的混乱)来完成,但如果你像我一样,你更喜欢避免不必要的(第三方)子类,只是为了给现有的UIKit类添加一些额外的功能。此外,这有一个漂亮的地方,它添加了任何现有的UILabel的点击链接,例如现有的UITableViewCells!
我已经试着让它尽可能的最小化侵入性通过使用现有的NSLinkAttributeName属性在NSAttributedString中已经可用。所以很简单:
NSURL *myURL = [NSURL URLWithString:@"http://www.google.com"];
NSMutableAttributedString *myString = [NSMutableAttributedString.alloc initWithString:@"This string has a clickable link: "];
[myString appendAttributedString:[NSAttributedString.alloc initWithString:@"click here" attributes:@{NSLinkAttributeName:myURL}]];
...
myLabel.attributedText = myString;
myLabel.enableLinks = YES; // yes, that's all! :-)
基本上,它通过添加一个UIGestureRecognizer到你的UILabel来工作。最难的工作是在gestureRecognizerShouldBegin:中完成的,它会重新布局attributedText字符串,以找出被点击的字符。如果这个字符是NSLinkAttributeName的一部分,那么手势识别器将随后触发,检索相应的URL(从NSLinkAttributeName值),并打开每个通常的[UIApplication。sharedApplication openURL:url进程。
注意:通过在gestureRecognizerShouldBegin:中执行所有这些操作,如果你没有碰巧点击标签中的链接,事件就会被传递。因此,例如,你的UITableViewCell将捕获点击链接,但其他行为正常(选择单元格,取消选择,滚动,…)。
我把它放在了GitHub仓库里。 改编自Kai Burghardt的SO帖子。
其他回答
下面是超链接UILabel的示例代码: 来源:http://sickprogrammersarea.blogspot.in/2014/03/adding-links-to-uilabel.html
#import "ViewController.h"
#import "TTTAttributedLabel.h"
@interface ViewController ()
@end
@implementation ViewController
{
UITextField *loc;
TTTAttributedLabel *data;
}
- (void)viewDidLoad
{
[super viewDidLoad];
UILabel *lbl = [[UILabel alloc] initWithFrame:CGRectMake(5, 20, 80, 25) ];
[lbl setText:@"Text:"];
[lbl setFont:[UIFont fontWithName:@"Verdana" size:16]];
[lbl setTextColor:[UIColor grayColor]];
loc=[[UITextField alloc] initWithFrame:CGRectMake(4, 20, 300, 30)];
//loc.backgroundColor = [UIColor grayColor];
loc.borderStyle=UITextBorderStyleRoundedRect;
loc.clearButtonMode=UITextFieldViewModeWhileEditing;
//[loc setText:@"Enter Location"];
loc.clearsOnInsertion = YES;
loc.leftView=lbl;
loc.leftViewMode=UITextFieldViewModeAlways;
[loc setDelegate:self];
[self.view addSubview:loc];
[loc setRightViewMode:UITextFieldViewModeAlways];
CGRect frameimg = CGRectMake(110, 70, 70,30);
UIButton *srchButton = [UIButton buttonWithType:UIButtonTypeRoundedRect];
srchButton.frame=frameimg;
[srchButton setTitle:@"Go" forState:UIControlStateNormal];
[srchButton setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
srchButton.backgroundColor=[UIColor clearColor];
[srchButton addTarget:self action:@selector(go:) forControlEvents:UIControlEventTouchDown];
[self.view addSubview:srchButton];
data = [[TTTAttributedLabel alloc] initWithFrame:CGRectMake(5, 120,self.view.frame.size.width,200) ];
[data setFont:[UIFont fontWithName:@"Verdana" size:16]];
[data setTextColor:[UIColor blackColor]];
data.numberOfLines=0;
data.delegate = self;
data.enabledTextCheckingTypes=NSTextCheckingTypeLink|NSTextCheckingTypePhoneNumber;
[self.view addSubview:data];
}
- (void)attributedLabel:(TTTAttributedLabel *)label didSelectLinkWithURL:(NSURL *)url
{
NSString *val=[[NSString alloc]initWithFormat:@"%@",url];
if ([[url scheme] hasPrefix:@"mailto"]) {
NSLog(@" mail URL Selected : %@",url);
MFMailComposeViewController *comp=[[MFMailComposeViewController alloc]init];
[comp setMailComposeDelegate:self];
if([MFMailComposeViewController canSendMail])
{
NSString *recp=[[val substringToIndex:[val length]] substringFromIndex:7];
NSLog(@"Recept : %@",recp);
[comp setToRecipients:[NSArray arrayWithObjects:recp, nil]];
[comp setSubject:@"From my app"];
[comp setMessageBody:@"Hello bro" isHTML:NO];
[comp setModalTransitionStyle:UIModalTransitionStyleCrossDissolve];
[self presentViewController:comp animated:YES completion:nil];
}
}
else{
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:val]];
}
}
-(void)mailComposeController:(MFMailComposeViewController *)controller didFinishWithResult:(MFMailComposeResult)result error:(NSError *)error{
if(error)
{
UIAlertView *alrt=[[UIAlertView alloc]initWithTitle:@"Erorr" message:@"Some error occureed" delegate:nil cancelButtonTitle:@"" otherButtonTitles:nil, nil];
[alrt show];
[self dismissViewControllerAnimated:YES completion:nil];
}
else{
[self dismissViewControllerAnimated:YES completion:nil];
}
}
- (void)attributedLabel:(TTTAttributedLabel *)label didSelectLinkWithPhoneNumber:(NSString *)phoneNumber
{
NSLog(@"Phone Number Selected : %@",phoneNumber);
UIDevice *device = [UIDevice currentDevice];
if ([[device model] isEqualToString:@"iPhone"] ) {
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:[NSString stringWithFormat:@"tel:%@",phoneNumber]]];
} else {
UIAlertView *Notpermitted=[[UIAlertView alloc] initWithTitle:@"Alert" message:@"Your device doesn't support this feature." delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
[Notpermitted show];
}
}
-(void)go:(id)sender
{
[data setText:loc.text];
}
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
NSLog(@"Reached");
[loc resignFirstResponder];
}
以下是基于@Luca Davanzo的回答,重写touchesBegan事件而不是轻触手势:
import UIKit
public protocol TapableLabelDelegate: NSObjectProtocol {
func tapableLabel(_ label: TapableLabel, didTapUrl url: String, atRange range: NSRange)
}
public class TapableLabel: UILabel {
private var links: [String: NSRange] = [:]
private(set) var layoutManager = NSLayoutManager()
private(set) var textContainer = NSTextContainer(size: CGSize.zero)
private(set) var textStorage = NSTextStorage() {
didSet {
textStorage.addLayoutManager(layoutManager)
}
}
public weak var delegate: TapableLabelDelegate?
public override var attributedText: NSAttributedString? {
didSet {
if let attributedText = attributedText {
textStorage = NSTextStorage(attributedString: attributedText)
} else {
textStorage = NSTextStorage()
links = [:]
}
}
}
public override var lineBreakMode: NSLineBreakMode {
didSet {
textContainer.lineBreakMode = lineBreakMode
}
}
public override var numberOfLines: Int {
didSet {
textContainer.maximumNumberOfLines = numberOfLines
}
}
public override init(frame: CGRect) {
super.init(frame: frame)
setup()
}
public required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
setup()
}
public override func layoutSubviews() {
super.layoutSubviews()
textContainer.size = bounds.size
}
/// addLinks
///
/// - Parameters:
/// - text: text of link
/// - url: link url string
public func addLink(_ text: String, withURL url: String) {
guard let theText = attributedText?.string as? NSString else {
return
}
let range = theText.range(of: text)
guard range.location != NSNotFound else {
return
}
links[url] = range
}
private func setup() {
isUserInteractionEnabled = true
layoutManager.addTextContainer(textContainer)
textContainer.lineFragmentPadding = 0
textContainer.lineBreakMode = lineBreakMode
textContainer.maximumNumberOfLines = numberOfLines
}
public override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
guard let locationOfTouch = touches.first?.location(in: self) else {
return
}
textContainer.size = bounds.size
let indexOfCharacter = layoutManager.glyphIndex(for: locationOfTouch, in: textContainer)
for (urlString, range) in links {
if NSLocationInRange(indexOfCharacter, range), let url = URL(string: urlString) {
delegate?.tapableLabel(self, didTapUrl: urlString, atRange: range)
}
}
}}
基于Charles Gamble的答案,这是我使用的(我删除了一些让我困惑并给我错误索引的行):
- (BOOL)didTapAttributedTextInLabel:(UILabel *)label inRange:(NSRange)targetRange TapGesture:(UIGestureRecognizer*) gesture{
NSParameterAssert(label != nil);
// create instances of NSLayoutManager, NSTextContainer and NSTextStorage
NSLayoutManager *layoutManager = [[NSLayoutManager alloc] init];
NSTextStorage *textStorage = [[NSTextStorage alloc] initWithAttributedString:label.attributedText];
// configure layoutManager and textStorage
[textStorage addLayoutManager:layoutManager];
// configure textContainer for the label
NSTextContainer *textContainer = [[NSTextContainer alloc] initWithSize:CGSizeMake(label.frame.size.width, label.frame.size.height)];
textContainer.lineFragmentPadding = 0.0;
textContainer.lineBreakMode = label.lineBreakMode;
textContainer.maximumNumberOfLines = label.numberOfLines;
// find the tapped character location and compare it to the specified range
CGPoint locationOfTouchInLabel = [gesture locationInView:label];
[layoutManager addTextContainer:textContainer]; //(move here, not sure it that matter that calling this line after textContainer is set
NSInteger indexOfCharacter = [layoutManager characterIndexForPoint:locationOfTouchInLabel
inTextContainer:textContainer
fractionOfDistanceBetweenInsertionPoints:nil];
if (NSLocationInRange(indexOfCharacter, targetRange)) {
return YES;
} else {
return NO;
}
}
一般来说,如果我们想在UILabel显示的文本中有一个可点击的链接,我们需要解决两个独立的任务:
更改部分文本的外观,使其看起来像链接 检测和处理链接上的触摸(打开URL是一个特殊情况)
第一个很简单。从ios6开始,UILabel支持显示带属性的字符串。你所需要做的就是创建并配置一个NSMutableAttributedString实例:
NSMutableAttributedString *attributedString = [[NSMutableAttributedString alloc] initWithString:@"String with a link" attributes:nil];
NSRange linkRange = NSMakeRange(14, 4); // for the word "link" in the string above
NSDictionary *linkAttributes = @{ NSForegroundColorAttributeName : [UIColor colorWithRed:0.05 green:0.4 blue:0.65 alpha:1.0],
NSUnderlineStyleAttributeName : @(NSUnderlineStyleSingle) };
[attributedString setAttributes:linkAttributes range:linkRange];
// Assign attributedText to UILabel
label.attributedText = attributedString;
就是这样!上面的代码使UILabel显示带有链接的String
现在我们应该检测这个链接上的触摸。其思想是捕获UILabel中的所有点击,并确定点击的位置是否足够接近链接。为了捕捉触摸,我们可以在标签中添加点击手势识别器。确保为标签启用userInteraction,默认情况下是关闭的:
label.userInteractionEnabled = YES;
[label addGestureRecognizer:[[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleTapOnLabel:)]];
现在最复杂的事情是:找出点击是否在显示链接的地方,而不是在标签的任何其他部分。如果我们有单行UILabel,这个任务可以通过硬编码链接显示的区域边界来相对容易地解决,但是让我们更优雅地解决这个问题,对于一般情况-多行UILabel,而不需要对链接布局有初步的了解。
其中一种方法是使用iOS 7中引入的Text Kit API功能:
// Create instances of NSLayoutManager, NSTextContainer and NSTextStorage
NSLayoutManager *layoutManager = [[NSLayoutManager alloc] init];
NSTextContainer *textContainer = [[NSTextContainer alloc] initWithSize:CGSizeZero];
NSTextStorage *textStorage = [[NSTextStorage alloc] initWithAttributedString:attributedString];
// Configure layoutManager and textStorage
[layoutManager addTextContainer:textContainer];
[textStorage addLayoutManager:layoutManager];
// Configure textContainer
textContainer.lineFragmentPadding = 0.0;
textContainer.lineBreakMode = label.lineBreakMode;
textContainer.maximumNumberOfLines = label.numberOfLines;
将创建和配置的NSLayoutManager, NSTextContainer和NSTextStorage实例保存在类的属性中(很可能是UIViewController的后代)-我们将在其他方法中需要它们。
现在,每当标签改变它的框架,更新textContainer的大小:
- (void)viewDidLayoutSubviews
{
[super viewDidLayoutSubviews];
self.textContainer.size = self.label.bounds.size;
}
最后,检测点击是否恰好在链接上:
- (void)handleTapOnLabel:(UITapGestureRecognizer *)tapGesture
{
CGPoint locationOfTouchInLabel = [tapGesture locationInView:tapGesture.view];
CGSize labelSize = tapGesture.view.bounds.size;
CGRect textBoundingBox = [self.layoutManager usedRectForTextContainer:self.textContainer];
CGPoint textContainerOffset = CGPointMake((labelSize.width - textBoundingBox.size.width) * 0.5 - textBoundingBox.origin.x,
(labelSize.height - textBoundingBox.size.height) * 0.5 - textBoundingBox.origin.y);
CGPoint locationOfTouchInTextContainer = CGPointMake(locationOfTouchInLabel.x - textContainerOffset.x,
locationOfTouchInLabel.y - textContainerOffset.y);
NSInteger indexOfCharacter = [self.layoutManager characterIndexForPoint:locationOfTouchInTextContainer
inTextContainer:self.textContainer
fractionOfDistanceBetweenInsertionPoints:nil];
NSRange linkRange = NSMakeRange(14, 4); // it's better to save the range somewhere when it was originally used for marking link in attributed string
if (NSLocationInRange(indexOfCharacter, linkRange)) {
// Open an URL, or handle the tap on the link in any other way
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:@"https://stackoverflow.com/"]];
}
}
我们使用来自zekel的UITapGestureRecognizer类别的方便解决方案。 它使用了NSTextContainer,就像这个问题的许多答案一样。
但是,这将返回错误的字符索引。显然是因为NSTextContainer缺少关于字体样式的信息,正如这些其他帖子所指出的:
https://stackoverflow.com/a/34238382/2439941 https://stackoverflow.com/a/47358270/2439941
后改变:
NSTextStorage *textStorage = [[NSTextStorage alloc] initWithAttributedString:label.attributedText];
To:
// Apply the font of the label to the attributed text:
NSMutableAttributedString *attributedText = [[NSMutableAttributedString alloc] initWithAttributedString:label.attributedText];
NSMutableParagraphStyle *paragraphStyle = NSMutableParagraphStyle.new;
paragraphStyle.alignment = self.label.textAlignment;
[attributedText addAttributes:@{NSFontAttributeName: label.font, NSParagraphStyleAttributeName: paragraphStyle}
range:NSMakeRange(0, label.attributedText.string.length)];
// Init with attributed text from label:
NSTextStorage *textStorage = [[NSTextStorage alloc] initWithAttributedString:attributedText];
结果明显更好,点击区域现在正确地从目标字符串的第一个字符开始。但最后一个字符仍然返回NO。我们期望这与我们的目标字符串具有将字体权重设置为UIFontWeightSemibold的属性有关。而上面的代码改进应用标签。整个字符串上的字体,它有一个规则的权重。
为了解决这个问题,我们进一步改进了上面的代码片段,通过遍历所有属性范围,以支持文本中的多种字体样式:
// According to https://stackoverflow.com/a/47358270/2439941 it's required to apply the paragraph style and font of the UILabel.
// However, the attributed string might contain font formatting as well, e.g. to emphasize a word in a different font style.
// Therefor copy all attributes:
NSMutableAttributedString *attributedText = [[NSMutableAttributedString alloc] initWithAttributedString:label.attributedText];
[label.attributedText enumerateAttributesInRange:NSMakeRange(0, label.attributedText.length)
options:0
usingBlock:^(NSDictionary<NSAttributedStringKey,id> * _Nonnull attrs, NSRange range, BOOL * _Nonnull stop) {
// Add each attribute:
[attributedText addAttributes:attrs
range:range];
// In case the attributes of this range do NOT contain a font specifier, apply the font from the UILabel:
if (![attrs objectForKey:NSFontAttributeName]) {
[attributedText addAttributes:@{ NSFontAttributeName : label.font }
range:range];
}
}];
// Init the storage with the font attributed text:
NSTextStorage *textStorage = [[NSTextStorage alloc] initWithAttributedString:attributedText];
现在,该方法为半粗体字符串范围内的每个字符返回YES,这是预期的结果。
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