An autoresizing mask is used to determine how a view is resized relative to its parent view when its parent view resizes. The enumeration values are masked together.

To have a view resize to fill its container, set it to NSViewWidthSizable

NSViewHeightSizable.

To have a view float in the center, set it to NSViewNotSizable.

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Here is a handy function to create a string from a mask value. Helpful in certain instances for debugging:

NSString* StringFromAutoresizingMask(NSUInteger mask) { if (mask == NSViewNotSizable) return @”NSViewNotSizable”; NSString *sep = @” | “; NSMutableString *str = [NSMutableString string]; if (mask & NSViewWidthSizable) [str appendFormat:@”NSViewWidthSizable%@”, sep]; if (mask & NSViewHeightSizable) [str appendFormat:@”NSViewHeightSizable%@”, sep]; if (mask & NSViewMinXMargin) [str appendFormat:@”NSViewMinXMargin%@”, sep]; if (mask & NSViewMaxXMargin) [str appendFormat:@”NSViewMaxXMargin%@”, sep]; if (mask & NSViewMinYMargin) [str appendFormat:@”NSViewMinYMargin%@”, sep]; if (mask & NSViewMaxYMargin) [str appendFormat:@”NSViewMaxYMargin%@”, sep]; if ([str hasSuffix:sep]) [str deleteCharactersInRange:NSMakeRange([str length]-[sep length], [sep length])]; return str; }