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
(我的回答建立在@NAlexN的精彩回答之上。我不会在这里重复他对每一步的详细解释。)
我发现这是最方便和直接的添加支持可点击的UILabel文本作为类别UITapGestureRecognizer。(你不必使用UITextView的数据检测器,就像一些答案所建议的那样。)
添加以下方法到你的UITapGestureRecognizer类别:
/**
Returns YES if the tap gesture was within the specified range of the attributed text of the label.
*/
- (BOOL)didTapAttributedTextInLabel:(UILabel *)label inRange:(NSRange)targetRange {
NSParameterAssert(label != nil);
CGSize labelSize = label.bounds.size;
// create instances of NSLayoutManager, NSTextContainer and NSTextStorage
NSLayoutManager *layoutManager = [[NSLayoutManager alloc] init];
NSTextContainer *textContainer = [[NSTextContainer alloc] initWithSize:CGSizeZero];
NSTextStorage *textStorage = [[NSTextStorage alloc] initWithAttributedString:label.attributedText];
// configure layoutManager and textStorage
[layoutManager addTextContainer:textContainer];
[textStorage addLayoutManager:layoutManager];
// configure textContainer for the label
textContainer.lineFragmentPadding = 0.0;
textContainer.lineBreakMode = label.lineBreakMode;
textContainer.maximumNumberOfLines = label.numberOfLines;
textContainer.size = labelSize;
// find the tapped character location and compare it to the specified range
CGPoint locationOfTouchInLabel = [self locationInView:label];
CGRect textBoundingBox = [layoutManager usedRectForTextContainer: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 = [layoutManager characterIndexForPoint:locationOfTouchInTextContainer
inTextContainer:textContainer
fractionOfDistanceBetweenInsertionPoints:nil];
if (NSLocationInRange(indexOfCharacter, targetRange)) {
return YES;
} else {
return NO;
}
}
示例代码
// (in your view controller)
// create your label, gesture recognizer, attributed text, and get the range of the "link" in your label
myLabel.userInteractionEnabled = YES;
[myLabel addGestureRecognizer:
[[UITapGestureRecognizer alloc] initWithTarget:self
action:@selector(handleTapOnLabel:)]];
// create your attributed text and keep an ivar of your "link" text range
NSAttributedString *plainText;
NSAttributedString *linkText;
plainText = [[NSMutableAttributedString alloc] initWithString:@"Add label links with UITapGestureRecognizer"
attributes:nil];
linkText = [[NSMutableAttributedString alloc] initWithString:@" Learn more..."
attributes:@{
NSForegroundColorAttributeName:[UIColor blueColor]
}];
NSMutableAttributedString *attrText = [[NSMutableAttributedString alloc] init];
[attrText appendAttributedString:plainText];
[attrText appendAttributedString:linkText];
// ivar -- keep track of the target range so you can compare in the callback
targetRange = NSMakeRange(plainText.length, linkText.length);
手势回调
// handle the gesture recognizer callback and call the category method
- (void)handleTapOnLabel:(UITapGestureRecognizer *)tapGesture {
BOOL didTapLink = [tapGesture didTapAttributedTextInLabel:myLabel
inRange:targetRange];
NSLog(@"didTapLink: %d", didTapLink);
}
斯威夫特5.2
我在之前的回答中发现了多行文本标签的几个问题,所以我给出了我最终的工作解决方案。
它解决了多行和文本对齐的问题。
func didTapAttributedTextInLabel(label: UILabel, inRange targetRange: NSRange) -> Bool {
// Create instances of NSLayoutManager, NSTextContainer and NSTextStorage
let layoutManager = NSLayoutManager()
let textContainer = NSTextContainer(size: CGSize.zero)
let textStorage = NSTextStorage(attributedString: label.attributedText!)
// Configure layoutManager and textStorage
layoutManager.addTextContainer(textContainer)
textStorage.addLayoutManager(layoutManager)
// Configure textContainer
textContainer.lineFragmentPadding = 0.0
textContainer.lineBreakMode = label.lineBreakMode
textContainer.maximumNumberOfLines = label.numberOfLines
let labelSize = label.bounds.size
textContainer.size = labelSize
// Find the tapped character location and compare it to the specified range
let locationOfTouchInLabel = self.location(in: label)
let textBoundingBox = layoutManager.usedRect(for: textContainer)
let textAligmentOffset = aligmentOffset(for: label)
let textContainerOffset = CGPoint(x: (labelSize.width - textBoundingBox.size.width) * textAligmentOffset - textBoundingBox.origin.x,
y: (labelSize.height - textBoundingBox.size.height) * textAligmentOffset - textBoundingBox.origin.y)
let locationOfTouchInTextContainer = CGPoint(x: (locationOfTouchInLabel.x - textContainerOffset.x),
y: 0 )
// Adjust for multiple lines of text
let lineModifier = Int(floor(locationOfTouchInLabel.y / label.font.lineHeight)) - 1
let rightMostFirstLinePoint = CGPoint(x: labelSize.width,
y: 0)
let charsPerLine = layoutManager.characterIndex(for: rightMostFirstLinePoint, in: textContainer, fractionOfDistanceBetweenInsertionPoints: nil)
let indexOfCharacter = layoutManager.characterIndex(for: locationOfTouchInTextContainer, in: textContainer, fractionOfDistanceBetweenInsertionPoints: nil)
let adjustedRange = indexOfCharacter + (lineModifier * charsPerLine)
return NSLocationInRange(adjustedRange, targetRange)
}
private func aligmentOffset(for label: UILabel) -> CGFloat {
switch label.textAlignment {
case .left, .natural, .justified:
return 0.0
case .center:
return 0.5
case .right:
return 1.0
@unknown default:
return 0.0
}
}
我强烈建议使用自动检测文本中的url并将其转换为链接的库。 试一试:
TTTAttributedLabel (pod) ZSWTappableLabel (under).
两者都得到了麻省理工学院的许可。
UIButtonTypeCustom是一个可点击的标签,如果你没有为它设置任何图像。
我创建了一个名为ResponsiveLabel的UILabel子类,它是基于ios7中引入的textkit API。它使用了NAlexN建议的相同方法。它提供了在文本中指定搜索模式的灵活性。可以指定应用于这些模式的样式,以及在敲击模式时要执行的操作。
//Detects email in text
NSString *emailRegexString = @"[A-Z0-9._%+-]+@[A-Z0-9.-]+\\.[A-Z]{2,4}";
NSError *error;
NSRegularExpression *regex = [[NSRegularExpression alloc]initWithPattern:emailRegexString options:0 error:&error];
PatternDescriptor *descriptor = [[PatternDescriptor alloc]initWithRegex:regex withSearchType:PatternSearchTypeAll withPatternAttributes:@{NSForegroundColorAttributeName:[UIColor redColor]}];
[self.customLabel enablePatternDetection:descriptor];
如果你想让一个字符串可点击,你可以这样做。这段代码将属性应用到字符串“text”的每个出现处。
PatternTapResponder tapResponder = ^(NSString *string) {
NSLog(@"tapped = %@",string);
};
[self.customLabel enableStringDetection:@"text" withAttributes:@{NSForegroundColorAttributeName:[UIColor redColor],
RLTapResponderAttributeName: tapResponder}];
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