View Full Version : Know iPhone OS Resource Limits

13 Jul 2010, 11:01 PM

Just thought to share some information regarding IPhone OS, how it handles an web app.

Your webpage performing well on the desktop is no guarantee that it will perform well on iPhone OS. Keep in mind that iPhone OS uses EDGE (lower bandwidth, higher latency), 3G (higher bandwidth, higher latency), and Wi-Fi (higher bandwidth, lower latency) to connect to the Internet. Therefore, you need to minimize the size of your webpage. Including unused or unnecessary images, CSS, and JavaScript in your webpages adversely affects your site’s performance on iPhone OS.
Because of the memory available on iPhone OS, there are limits on the number of resources it can process:

The maximum size for decoded GIF, PNG, and TIFF images is 3 megapixels.
That is, ensure that width * height ? 3 * 1024 * 1024. Note that the decoded size is far larger than the encoded size of an image.
The maximum decoded image size for JPEG is 32 megapixels using subsampling.
JPEG images can be up to 32 megapixels due to subsampling, which allows JPEG images to decode to a size that has one sixteenth the number of pixels. JPEG images larger than 2 megapixels are subsampled—that is, decoded to a reduced size. JPEG subsampling allows the user to view images from the latest digital cameras.
The maximum size for a canvas element is 3 megapixels.
The height and width of a canvas object is 150 x 300 pixels if not specified.
Individual resource files must be less than 10 MB.
This limit applies to HTML, CSS, JavaScript, or nonstreamed media.
JavaScript execution time is limited to 10 seconds for each top-level entry point.
If your script executes for more than 10 seconds, Safari on iPhone OS stops executing the script at a random place in your code, so unintended consequences may result.
This limit is imposed because JavaScript execution may cause the main thread to block, so when scripts are running, the user is not able to interact with the webpage.
Read “Debugging” (http://developer.apple.com/safari/library/documentation/AppleApplications/Reference/SafariWebContent/DebuggingSafarioniPhoneContent/DebuggingSafarioniPhoneContent.html#//apple_ref/doc/uid/TP40006515-SW1) for how to debug JavaScript on iPhone OS.
The maximum number of documents that can be open at once is eight.

You could find more under

I'm not aware of Andriod Browser and its capabilities, hope some one could provide more information regarding this.