给定文字测量它的大小

// Wrapping to fit horizontal and vertical size. Text will be wrapped and truncated using the NSLineBreakMode. If the height is less than a line of text, it may return
// a vertical size that is bigger than the one passed in.
// If you size your text using the constrainedToSize: methods below, you should draw the text using the drawInRect: methods using the same line break mode for consistency
- (CGSize)sizeWithFont:(UIFont *)font constrainedToSize:(CGSize)size NS_DEPRECATED_IOS(2_0, 7_0, "Use -boundingRectWithSize:options:attributes:context:"); // Uses NSLineBreakModeWordWrap
- (CGSize)sizeWithFont:(UIFont *)font constrainedToSize:(CGSize)size lineBreakMode:(NSLineBreakMode)lineBreakMode NS_DEPRECATED_IOS(2_0, 7_0, "Use -boundingRectWithSize:options:attributes:context:"); // NSTextAlignment is not needed to determine size

- (void)scrollToRowAtIndexPath:(NSIndexPath *)indexPath atScrollPosition:(UITableViewScrollPosition)scrollPosition animated:(BOOL)animated;
- (void)scrollToNearestSelectedRowAtScrollPosition:(UITableViewScrollPosition)scrollPosition animated:(BOOL)animated;

给定文字测量它的大小

原文：http://www.cnblogs.com/ygsios/p/4303235.html