iPhone和iPad下各种常见控件的宽度和标准是一样的，所以这里就用iPhone说明。

 

Sizes of iPhone UI Elements

Element	Size (in points)
Window (including status bar)	320 x 480 pts
Status Bar ()	20 pts
View inside window  (visible status bar)	320 x 460
Navigation Bar	44 pts
Nav Bar Image / Toolbar Image	up to 20 x 20 pts (transparent PNG)
Tab Bar	49 pts
Tab Bar Icon	up to 30 x 30 pts (transparent PNGs)
Text Field	31 pts
Height of a view inside  a navigation bar	416 pts
Height of a view inside  a tab bar	411 pts
Height of a view inside  a navbar and a tab bar	367 pts
Portrait Keyboard height	216 pts
Landscape Keyboard height	140 pts

Points vs. Pixels

The iPhone 4 introduced a high resolution display with twice the pixels of previous iPhones. However you don't have to modify your 

code to support high-res displays; the coordinate system goes by points rather than pixels, and the dimensi***** in points of the screen and all UI elements remain the same.

iOS 4 supports high resolution displays (like the iPhone 4 display) via the 

scale property on UIScreen, UIView, UIImage, and CALayer classes. If the object is displaying 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 @2x versi***** of the images in your project. See the   or 

Apple documentation for   for more info.

Adjusting Sizes

Click here to see how to adjust  .

Additional References

Apple Documentation: 

Apple Documentation:  says "Typically, the size of a toolbar and navigation bar image is 20 x 20 points."

Apple Documentation:  says "The size of an tab bar image is typically 30 x 30 points."