UILabel多行并根据高度动态显示文本

+(float) calculateHeightOfTextFromWidth:(NSString*) text: (UIFont*)withFont: (float)width :(UILineBreakMode)lineBreakMode
{
[text retain];
[withFont retain];
CGSize suggestedSize = [text sizeWithFont:withFont constrainedToSize:CGSizeMake(width, FLT_MAX) lineBreakMode:lineBreakMode];
 
[text release];
[withFont release];
 
return suggestedSize.height;
}