Detecting taps on attributed text in a UITextView in iOS
I have a UITextView which displays an NSAttributedString. This string contains words that I'd like to make tappable, such that when they are tapped I get called back so that I can perform an action. I realise that UITextView can detect taps on a URL and call back my delegate, but these aren't URLs.
It seems to me that with iOS7 and the power of TextKit this should now be possible, however I can't find any examples and I'm not sure where to start.
I understand that it's now possible to create custom attributes in the string (although I haven't done this yet), and perhaps these will be useful to detecting if one of the magic words has been tapped? In any case, I still don't know how to intercept that tap and detect on which word the tap occurred.
Note that iOS 6 compatibility is not required.
I just wanted to help others a little more. Following on from Shmidt's response it's possible to do exactly as I had asked in my original question.
1) Create an attributed string with custom attributes applied to the clickable words. eg.
NSAttributedString* attributedString = [[NSAttributedString alloc] initWithString:@"a clickable word" attributes:@{ @"myCustomTag" : @(YES) }];
[paragraph appendAttributedString:attributedString];
2) Create a UITextView to display that string, and add a UITapGestureRecognizer to it. Then handle the tap:
- (void)textTapped:(UITapGestureRecognizer *)recognizer
{
UITextView *textView = (UITextView *)recognizer.view;
// Location of the tap in text-container coordinates
NSLayoutManager *layoutManager = textView.layoutManager;
CGPoint location = [recognizer locationInView:textView];
location.x -= textView.textContainerInset.left;
location.y -= textView.textContainerInset.top;
// Find the character that's been tapped on
NSUInteger characterIndex;
characterIndex = [layoutManager characterIndexForPoint:location
inTextContainer:textView.textContainer
fractionOfDistanceBetweenInsertionPoints:NULL];
if (characterIndex < textView.textStorage.length) {
NSRange range;
id value = [textView.attributedText attribute:@"myCustomTag" atIndex:characterIndex effectiveRange:&range];
// Handle as required...
NSLog(@"%@, %d, %d", value, range.location, range.length);
}
}
So easy when you know how!
Updated for Swift 3
Detecting taps on attributed text with Swift
Sometimes for beginners it is a little hard to know how to do get things set up (it was for me anyway), so this example is a little fuller and uses Swift 3.
Add a UITextView to your project.
Settings
Use the following settings in the Attributes inspector:
Outlet
Connect the UITextView to the ViewController with an outlet named textView .
Code
Add code to your View Controller to detect the tap. Note the UIGestureRecognizerDelegate .
import UIKit
class ViewController: UIViewController, UIGestureRecognizerDelegate {
@IBOutlet weak var textView: UITextView!
override func viewDidLoad() {
super.viewDidLoad()
// Create an attributed string
let myString = NSMutableAttributedString(string: "Swift attributed text")
// Set an attribute on part of the string
let myRange = NSRange(location: 0, length: 5) // range of "Swift"
let myCustomAttribute = [ "MyCustomAttributeName": "some value"]
myString.addAttributes(myCustomAttribute, range: myRange)
textView.attributedText = myString
// Add tap gesture recognizer to Text View
let tap = UITapGestureRecognizer(target: self, action: #selector(myMethodToHandleTap(_:)))
tap.delegate = self
textView.addGestureRecognizer(tap)
}
func myMethodToHandleTap(_ sender: UITapGestureRecognizer) {
let myTextView = sender.view as! UITextView
let layoutManager = myTextView.layoutManager
// location of tap in myTextView coordinates and taking the inset into account
var location = sender.location(in: myTextView)
location.x -= myTextView.textContainerInset.left;
location.y -= myTextView.textContainerInset.top;
// character index at tap location
let characterIndex = layoutManager.characterIndex(for: location, in: myTextView.textContainer, fractionOfDistanceBetweenInsertionPoints: nil)
// if index is valid then do something.
if characterIndex < myTextView.textStorage.length {
// print the character index
print("character index: (characterIndex)")
// print the character at the index
let myRange = NSRange(location: characterIndex, length: 1)
let substring = (myTextView.attributedText.string as NSString).substring(with: myRange)
print("character at index: (substring)")
// check if the tap location has a certain attribute
let attributeName = "MyCustomAttributeName"
let attributeValue = myTextView.attributedText.attribute(attributeName, at: characterIndex, effectiveRange: nil) as? String
if let value = attributeValue {
print("You tapped on (attributeName) and the value is: (value)")
}
}
}
}
Now if you tap on the "w" of "Swift", you should get the following result:
Notes
NSForegroundColorAttributeName (text color) that has a value of UIColor.greenColor() . Further study
This answer was based on several other answers to this question. Besides these, see also
This is a slightly modified version, building off of @tarmes answer. I couldn't get the value variable to return anything but null without the tweak below. Also, I needed the full attribute dictionary returned in order to determine the resulting action. I would have put this in the comments but don't appear to have the rep to do so. Apologies in advance if I have violated protocol.
Specific tweak is to use textView.textStorage instead of textView.attributedText . As a still learning iOS programmer, I am not really sure why this is, but perhaps someone else can enlighten us.
Specific modification in the tap handling method:
NSDictionary *attributesOfTappedText = [textView.textStorage attributesAtIndex:characterIndex effectiveRange:&range];
Full code in my view controller
- (void)viewDidLoad
{
[super viewDidLoad];
self.textView.attributedText = [self attributedTextViewString];
UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(textTapped:)];
[self.textView addGestureRecognizer:tap];
}
- (NSAttributedString *)attributedTextViewString
{
NSMutableAttributedString *paragraph = [[NSMutableAttributedString alloc] initWithString:@"This is a string with " attributes:@{NSForegroundColorAttributeName:[UIColor blueColor]}];
NSAttributedString* attributedString = [[NSAttributedString alloc] initWithString:@"a tappable string"
attributes:@{@"tappable":@(YES),
@"networkCallRequired": @(YES),
@"loadCatPicture": @(NO)}];
NSAttributedString* anotherAttributedString = [[NSAttributedString alloc] initWithString:@" and another tappable string"
attributes:@{@"tappable":@(YES),
@"networkCallRequired": @(NO),
@"loadCatPicture": @(YES)}];
[paragraph appendAttributedString:attributedString];
[paragraph appendAttributedString:anotherAttributedString];
return [paragraph copy];
}
- (void)textTapped:(UITapGestureRecognizer *)recognizer
{
UITextView *textView = (UITextView *)recognizer.view;
// Location of the tap in text-container coordinates
NSLayoutManager *layoutManager = textView.layoutManager;
CGPoint location = [recognizer locationInView:textView];
location.x -= textView.textContainerInset.left;
location.y -= textView.textContainerInset.top;
NSLog(@"location: %@", NSStringFromCGPoint(location));
// Find the character that's been tapped on
NSUInteger characterIndex;
characterIndex = [layoutManager characterIndexForPoint:location
inTextContainer:textView.textContainer
fractionOfDistanceBetweenInsertionPoints:NULL];
if (characterIndex < textView.textStorage.length) {
NSRange range;
NSDictionary *attributes = [textView.textStorage attributesAtIndex:characterIndex effectiveRange:&range];
NSLog(@"%@, %@", attributes, NSStringFromRange(range));
//Based on the attributes, do something
///if ([attributes objectForKey:...)] //make a network call, load a cat Pic, etc
}
}
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