What are the numbers in the Stretching box in the View sub-box Interface Builder's Attributes Inspector?
(as a side question - I suppose a respectable company such as Apple would have actually released documentation for its tools, as opposed to letting developers just guess everything; so, where's this documentation?...)
This blog post Karol seems to explain it pretty well. - http://macoscope.com/blog/stretchable-images-using-interface-builder/
Stretching properties are pretty simple (I don't think so, but the
articles does :).
The fraction of the original image left without stretching on the left
is specified by X The fraction of the original image that gets
stretched in the x-axis is specified by Width The fraction of the
original image left without stretching on the right is equal to 1 – X
– Width If we use 0 for Width the stretched area will interpolate
between the last pixel of the left part and the first pixel of the
right part The y-axis works analogously
Viewing a .storyboard
file in a text editor (figures it's an XML
file) revealed the answer: it is linked to UIView
's contentStretch property.
FYI - this was deprecated in iOS 6.0 https://developer.apple.com/library/ios/documentation/UIKit/Reference/UIView_Class/index.html#//apple_ref/occ/instp/UIView/contentStretch
(updated link)
Deprecation Documentation
Instance Property
contentStretch
The rectangle that defines the stretchable and nonstretchable regions of a view.
Deprecated
To achieve the same effect, use resizableImageWithCapInsets: instead.