IOS中经常用到的空间尺寸大小

ElementSize (in points)Window (including status bar)320 x 480 ptsStatus Bar
(How to hide the status bar)20 ptsView inside window 
(visible status bar)320 x 460Navigation Bar44 ptsNav Bar Image /
Toolbar Imageup to 20 x 20 pts (transparent PNG)Tab Bar49 ptsTab Bar Iconup to 30 x 30 pts (transparent PNGs)Text Field31 ptsHeight of a view inside 
a navigation bar416 ptsHeight of a view inside 
a tab bar411 ptsHeight of a view inside 
a navbar and atab bar367 ptsPortrait Keyboard height216 ptsLandscape Keyboard height140 ptsPointsvs. Pixels
The iPhone 4 introduced a high resolution display with twice thepixels of previous iPhones. However you don't have to modifyyour code tosupport high-res displays; the coordinate system goes by pointsrather than pixels, and the dimensi***** in points of the screenand all UI elements remain the same.
iOS 4supports high resolution displays (like the iPhone 4 display) viathe scale propertyon UIScreen, UIView, UIImage, and CALayer classes. If the object isdisplaying high-res content, its scale property is set to 2.0.Otherwise it defaults to 1.0.
All you need to do to support high-res displays is to provide @2xversi***** of the images in your project. Seethe checklist for updating to iOS4 or Apple documentationfor Supporting High Resolution Screens formore info.
Adjusting Sizes
Click here to see how toadjust View Frames and Bounds.
Additional References

Apple Documentation: Points vs. PixelsAppleDocumentation: UIBarButtonItem ClassReference says "Typically, the size of atoolbar and navigation bar image is 20 x 20 points."AppleDocumentation: UITabBarItem ClassReference says "The size of an tab bar imageis typically 30 x 30 points."