how to increase font size in UIWebView

Question

how to increase or decrease the UIWebview font size, not using scalePageToFit:NO;

score 74 · Answer 1 · answered Nov 24 '09 at 14:07

74

I have 2 buttons - A- and A+

@interface
NSUInteger textFontSize;

- (IBAction)changeTextFontSize:(id)sender
{
    switch ([sender tag]) {
        case 1: // A-
            textFontSize = (textFontSize > 50) ? textFontSize -5 : textFontSize;
            break;
        case 2: // A+
            textFontSize = (textFontSize < 160) ? textFontSize +5 : textFontSize;
            break;
    }

    NSString *jsString = [[NSString alloc] initWithFormat:@"document.getElementsByTagName('body')[0].style.webkitTextSizeAdjust= '%d%%'", 
                          textFontSize];
    [web stringByEvaluatingJavaScriptFromString:jsString];
    [jsString release];
}

answered Nov 24 '09 at 14:07

Taras Kalapun

1,761
15
19

4

Be sure to set `textFontSize` to an initial value (presumably 100) before calling this. – zekel Jun 18 '10 at 21:24
2

It is also possible to set `...style.fontSize` (or other CSS properties). In my case this meant I didn't have to convert the scale back to a proper font size between sessions. – aerique Jan 13 '12 at 16:01
Seems broken in iOS10 on iPad only. Anyone have any fix or alternative? Thanks! – Chris Comeau Sep 09 '16 at 14:07

score 11 · Answer 2 · edited Jul 10 '13 at 13:22

11

- (void)webViewDidFinishLoad:(UIWebView *)webView
{
    NSString *fontSize=@"143";
    NSString *jsString = [[NSString alloc]      initWithFormat:@"document.getElementsByTagName('body')[0].style.webkitTextSizeAdjust= '%d%%'",[fontSize intValue]];
    [myWebview stringByEvaluatingJavaScriptFromString:jsString];

}

edited Jul 10 '13 at 13:22

Guru

21,652
10
63
102

answered Jul 10 '13 at 13:14

Girish Chauhan

167
1
4

score 9 · Answer 3 · answered Feb 26 '09 at 06:08

There is currently no exposed way to directly manipulate the DOM in a UIWebView, nor any convenience methods for handling things like font sizes. I suggest filing Radars.

Having said that. you can modify the font size by changing the CSS, like any other webpage. If that is not possible (you don't control the content) you can write a small javascript function to change the CSS properties in the pages DOM, and execute it by calling:

- (NSString *)stringByEvaluatingJavaScriptFromString:(NSString *)script;

but if i change the CSS property through javascript, it lost the position where i was reading the content after increase/decrease the font. — Praveen-K, Aug 10 '11 at 07:41

BLC · Answer 4 · 2017-07-27T10:04:47.627

5

Swift 3

public func webViewDidFinishLoad(_ webView: UIWebView) {        
    let textSize: Int = 300
    webView.stringByEvaluatingJavaScript(from: "document.getElementsByTagName('body')[0].style.webkitTextSizeAdjust= '\(textSize)%%'")
}

Older Swift:

func webViewDidFinishLoad(webView: UIWebView) {
    let textSize: Int = 300

    webView.stringByEvaluatingJavaScriptFromString("document.getElementsByTagName('body')[0].style.webkitTextSizeAdjust= '\(textSize)%%'")
}

edited Jul 27 '17 at 10:04

answered Aug 27 '15 at 11:40

BLC

2,240
25
27

1

While this code may answer the question, providing additional context regarding why and/or how this code answers the question improves its long-term value. – JAL Aug 27 '15 at 16:15
Swift 3 `webView.stringByEvaluatingJavaScript(from: "document.getElementsByTagName('body')[0].style.webkitTextSizeAdjust= '\(textSize)%%'")` – Ariel Gemilang Mar 22 '17 at 07:53
Thanks @ArielGemilang. I updated you per your suggestion. – BLC Jul 27 '17 at 10:05

score 3 · Answer 5 · answered Jan 27 '20 at 19:43

3

Swift 5 Update. This is an updated answer from @BLCs suggestion.

Also fixes the double %% in his string.

func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!) {
    let textSize = 300
    let javascript = "document.getElementsByTagName('body')[0].style.webkitTextSizeAdjust= '\(textSize)%'"
    webView.evaluateJavaScript(javascript) { (response, error) in
        print()
    }
}

answered Jan 27 '20 at 19:43

Doolali

956
9
13

it's perfect answer – iPhone 7 Aug 19 '21 at 10:18

score 2 · Answer 6 · answered Apr 12 '17 at 22:12

in my case im using a UISlider for the fontSize, can be any float value

func webViewDidFinishLoad(_ webView: UIWebView) {

    if let fontSize: Float = (self.fontSizeSlider?.value) {
        webView.stringByEvaluatingJavaScript(from: "document.getElementsByTagName('body')[0].style.webkitTextSizeAdjust= '\(fontSize)%%'")
        print(fontSize)
    }

}

score 1 · Answer 7 · answered Jun 19 '13 at 10:35

1

Try the below code :

NSString *setTextSizeRule = [NSString stringWithFormat:@"addCSSRule('body', '-webkit-text-size-adjust: %d%%;')",currentTextSize];
[_webview stringByEvaluatingJavaScriptFromString:setTextSizeRule];

answered Jun 19 '13 at 10:35

Hiren

12,720
7
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score 1 · Answer 8 · answered Aug 25 '13 at 22:42

Here is mine for changing font size and color in UIWebView:

 NSString *myString=@"Hello World!";
 int textFontSize=2;
 NSString *myHTML=[NSString stringWithFormat: @"<html><body><script>var str = '%@'; document.write(str.fontsize(%d).fontcolor('green'));</script></body></html>",myString,textFontSize];    
 [myWebView loadHTMLString:myHTML baseURL:nil];

score 1 · Answer 9 · answered May 22 '14 at 12:32

1

Try this simple method

- (void)webViewDidFinishLoad:(UIWebView *)webView
{
    int fontValue = 150;
    NSString *webviewFontSize = [NSString stringWithFormat:@"addCSSRule('body', '-webkit-text-size-adjust: %d%%;')",fontValue];
    [your_webview stringByEvaluatingJavaScriptFromString:webviewFontSize];
}

answered May 22 '14 at 12:32

Rajesh Loganathan

11,129
4
78
90

This is not working for iOS 10.1.1 on iPad, is there any alternative? – coder Nov 18 '16 at 10:39

Jack · Answer 10 · 2020-11-10T15:59:02.167

1

In SWIFT -

let fontSize = 20
let fontSetting = "<span style=\"font-size: \(fontSize)\"</span>"
webView.loadHTMLString( fontSetting + myHTMLString, baseURL: nil)

edited Nov 10 '20 at 15:59

answered Mar 05 '19 at 10:19

Jack

13,571
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Nupur Sharma · Answer 11 · 2017-01-27T07:02:12.390

Change the font size of the fetched HTML data by changing the occurrence of font size in the fetched html string to your required font size (40 in this example) in a method.

strHtml = [self htmlEntityDecode:strHtml];//parsing the html string


-(NSString *)htmlEntityDecode:(NSString *)string
{    
string = [string stringByReplacingOccurrencesOfString:@"14px;"   withString:@"40"];
string = [string stringByReplacingOccurrencesOfString:@"15px;"   withString:@"40"];
string = [string stringByReplacingOccurrencesOfString:@"16px;"   withString:@"40"];
string = [string stringByReplacingOccurrencesOfString:@"17px;"   withString:@"40"];
string = [string stringByReplacingOccurrencesOfString:@"18px;"   withString:@"40"];
string = [string stringByReplacingOccurrencesOfString:@"19px;"   withString:@"40"];
string = [string stringByReplacingOccurrencesOfString:@"20px;"   withString:@"40"];

 return string;
}

So the html string: span style='font-size: 20px; Becomes: span style='font-size: 40

Note: Change the other occurrences like gt;, apos; too to get the desired string to load in your Webview.

how to increase font size in UIWebView

11 Answers11

Try this simple method

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