Objective-c categories that I found useful.
+ (NSDateFormatter*) formatter:(NSString*)dateFormat fixedLocale:(BOOL)isFixedLocale useUserTimeZone:(BOOL)isUserTimeZone;
- (CGFloat) pagesVertical;
- (CGFloat) pagesHorizontal;
- (CGFloat) currentPageVertical;
- (CGFloat) currentPageHorizontal;
- (void) frameAddX:(CGFloat)x;
- (void) frameAddY:(CGFloat)y;
- (void) frameAddWidth:(CGFloat)width;
- (void) frameAddHeight:(CGFloat)height;
- (void) frameSetX:(CGFloat)x;
- (void) frameSetY:(CGFloat)y;
- (void) frameSetWidth:(CGFloat)width;
- (void) frameSetHeight:(CGFloat)height;
- (void) frameSetOrigin:(CGPoint)origin;
- (void) frameSetSize:(CGSize)size;
- (CGFloat) frameX;
- (CGFloat) frameY;
- (CGFloat) frameWidth;
- (CGFloat) frameHeight;
- (CGPoint) frameOrigin;
- (CGSize) frameSize;