Datasheet

Chapter 1: Introducing Safari/WebKit Development for iPhone 3.0

Table 1-2: Finger Gestures

Gesture Result Web site App

Tap Equivalent to a mouse click Yes Yes

Drag Moves around the viewport Yes Yes

Flick Scrolls up and down a page or list Yes Yes

Double-tap Zooms in and centers a block of content Yes No

Pinch open Zooms in on content Yes No

Pinch close Zooms out to display more of a page Yes No

Touch and hold Displays an info bubble Yes No

Two-ﬁ nger scroll Scrolls up and down an

iframe or element with the

CSS

overflow:auto property

Yes Yes

Limitations and Constraints

Because iPhone is a mobile device, it is obviously going to have resource constraints that you need to

be fully aware of as you develop applications. Table 1-3 lists the resource limitations and technical con-

straints. What’s more, certain technologies (listed in Table 1-4) are unsupported, and you need to steer

away from them when you develop for iPhone and iPod touch.

Table 1-3: Resource Constraints

Resource Limitation

Downloaded text resource (HTML,

CSS, JavaScript ﬁ les)

10MB

JPEG images 128MB (all JPEG images over 2MB are subsam-

pled — decoding the image to 16x fewer pixels)

PNG, GIF, and TIFF images 8MB (in other words, width*height*4<8MB)

Animated GIFs Less than 2MB ensures that frame rate is maintained (over

2MB, only ﬁ rst frame is displayed)

Nonstreamed media ﬁ les 10MB

PDF, Word, Excel documents 30MB and up (very slow)

JavaScript stack and object allocation 10MB

JavaScript execution limit 5 seconds for each top-level entry point (

catch is called

after 5 seconds in a

try/catch block)

Open pages in Mobile Safari 8 pages

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