How can I enable zoom in on UIWebView which inside the UIScrollView?

Objective CIosCocoa TouchUiwebviewZooming

Objective C Problem Overview

I have a UIWebView which inside a UIScrollView (scrollview contain another component)

I tried to enable multitouch both on Interface Builder or Programmatic on UIWebView but it still cannot zoom for html, do I need to handle both zoom in at the UIScrollView and UIWebView? Or anything I haven't to set?

Objective C Solutions

Solution 1 - Objective C

You MUST set scalesPageToFit=YES for any pinching and zooming to work on a UIWebView

Solution 2 - Objective C

OK, you need to do both the above, but also the following. I had a web view in the main view, and that didn't work.

  1. As above, you first have to put a UIScrollView in the main view, then put the web view in the scroll view.
  2. As above, implement <UIScrollViewDelegate> in your view controller, drag the scroll view delegate to the view controller in Interface Builder, and implement the viewForZoomingInScrollView method. This must return the pointer to the UIScrollView (return myScrollView).
  3. I created IBOutlet properties for both the web view and the scroll view - link them in the NIB to your view controller.
  4. On the Scroll View, go to the Attributes Inspector, set your Max and Min zoom factors (I set 0.5 to 5.0, that works well).
  5. On the Web View, in the Attributes Inspector:
  6. In the Web View section, select Scales Pages To Fit
  7. In the View section, select for Mode, "Top Left"
  8. In the View section at the bottom, check off User Interaction Enabled, and Multiple Touch Enabled

Solution 3 - Objective C

With JavaScript you can control the zoom level, although the oly solution I have found doesn't look smooth.

Say you have in <head>:

<meta id="vp" name="viewport" content="width=768,initial-scale=1.0">

To zoom to 4x, and still allow the user to change zoom, change the content twice:

var vp = document.getElementById('vp');
vp.content = "width=767,minimum-scale=4.0,maximum-scale=4.0,user-scalable=yes";
vp.content = "width=768,minimum-scale=0.25,maximum-scale=10.0,user-scalable=yes";

Toggling the width is very important - otherwise Mobile Safari has serious repainting bugs (due to over-optimisation).

You cannot just set initial-scale again - it is ignored the second time.

Solution 4 - Objective C

You need to implement the viewForZoomingInScrollView method in your controller, or zooming won't do anything. (I don't really know why this should be needed, but there you go.)

For detailed information, see http://developer.apple.com/iphone/library/documentation/WindowsViews/Conceptual/UIScrollView_pg/ZoomZoom/ZoomZoom.html.

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Content TypeOriginal AuthorOriginal Content on Stackoverflow
QuestioncalendarwView Question on Stackoverflow
Solution 1 - Objective Cjohn geshrickView Answer on Stackoverflow
Solution 2 - Objective CJay ImermanView Answer on Stackoverflow
Solution 3 - Objective CrobocatView Answer on Stackoverflow
Solution 4 - Objective CapenwarrView Answer on Stackoverflow