Just to remember - size of iphone components

From idev101

Element Size (in pixels)
Window (including status bar) 320 x 480px
Status Bar
(How to hide the status bar) 20 px
View inside window
(visible status bar) 320 x 460
Navigation Bar 44 px
Nav Bar Image /
Toolbar Image up to 20 x 20 px (transparent PNG)
Tab Bar 49 px
Tab Bar Icon up to 30 x 30 px (transparent PNGs)
Text Field 31 px
Height of a view inside
a navigation bar 416 px
Height of a view inside
a tab bar 411 px
Height of a view inside
a navbar and a tab bar 367 px
Portrait Keyboard height 216 px
Landscape Keyboard height 140 px
Viewing / Adjusting Sizes in Interface Builder
Sizes for specific UI elements (buttons, text fields, images, etc.) can be adjusted in the size panel of the Inspector window (↑⌘I):
icon shortcut
⌘3 Size is the size and location (in X,Y coordinates) of the object on screen.

Size (and location) can also be adjusted programmatically:

[button setFrame:CGRectMake(x, y, width, height)];

The x, y position refers to the top left corner of the view being positioned.
Frame and Bounds

The frame is the outer container for the view - the position of the item within its enclosing superview. x is the distance left-right, where x = 0 is the left side. y is the distance up-down, where y = 0 is the top of the frame.

The bounds rectangle determines the origin and scale in the view's coordinate system within its frame rectangle. Setting this property changes the value of the frame property accordingly.

When you set the frame property, the size of the bounds property is set to match the size of the frame property. The center property is also adjusted to match the center point of the new frame.