Allows you adjust a UILabel's height according to its content and retreive expected height for given input

LabelSizer.h

@interface LabelSizer : NSObject {
    
}

+(float)getExpectedHeightForLabel:(UILabel*)label;
+(float)makeLabelCorrectSizeForCurrentWidth:(UILabel*)label;
+(float)getExpectedHeightForText:(NSString*)text withFontName:(NSString*)font atSize:(float)fontSize inContainerWidth:(float)width;

@end

LabelSizer.m

#import "LabelSizer.h"

@implementation LabelSizer

+(float)getExpectedHeightForLabel:(UILabel*)label{
    // Uses the incoming label's frame for width constraint
    [label setNumberOfLines:0];
    [label setLineBreakMode:UILineBreakModeWordWrap];

    CGSize maximumLabelSize = CGSizeMake(label.frame.size.width,9999);
    
    CGSize expectedLabelSize = [[label text]    sizeWithFont:[label font] 
                                                constrainedToSize:maximumLabelSize
                                                lineBreakMode:[label lineBreakMode]]; 
    return expectedLabelSize.height;
}
                                
+(float)makeLabelCorrectSizeForCurrentWidth:(UILabel*)label{
    float height = [self getExpectedHeightForLabel:label];
    CGRect newFrame = [label frame];
    newFrame.size.height = height;
    [label setFrame:newFrame];
    return newFrame.origin.y + newFrame.size.height;
}

+(float)getExpectedHeightForText:(NSString*)text withFontName:(NSString*)fontName atSize:(float)fontSize inContainerWidth:(float)width{
    
    CGSize constraint = CGSizeMake(width, 9999);
    
    CGSize size = [text sizeWithFont:[UIFont fontWithName:fontName size:fontSize] constrainedToSize:constraint lineBreakMode:UILineBreakModeWordWrap];
    
    return size.height;
}

@end

+ getExpectedHeightForText:withFontName:atSize:inContainerWidth: is used in the context that you would need to know the height of a UILabel but not require one a UILabel to be instantiated, this can be the case when implementing - tableView:heightForRowAtIndexPath: for example to work out the correct height for a cell that has one or more UILabel objects with dynamic heights.

The two other methods can be assigned to a category, which is more logical, this gist has been created on the following link: https://gist.github.com/1005494