Another version of danielphilips' UIlabel+dynamicSizeMe files (https://gist.github.com/danielphillips/1005520) optimized for iOS 7

UILabel+dynamicSizeMe.h

@interface UILabel (dynamicSizeMe)

-(float)resizeToFit;
-(float)expectedHeight;

@end

UILabel+dynamicSizeMe.m

#import "UILabel+dynamicSizeMe.h"

@implementation UILabel (dynamicSizeMe)

-(float)resizeToFit{
    float height = [self expectedHeight];
    CGRect newFrame = [self frame];
    newFrame.size.height = height;
    [self setFrame:newFrame];
    return newFrame.origin.y + newFrame.size.height;
}

-(float)expectedHeight{
    [self setNumberOfLines:0];
    [self setLineBreakMode:NSLineBreakByCharWrapping];
    
    UIFont *font = [UIFont systemFontOfSize:14.0]; // It's an example, set the font, you need
    
    NSDictionary *attributesDictionary = [NSDictionary dictionaryWithObjectsAndKeys:
                                          font, NSFontAttributeName,
                                          nil];

    CGSize maximumLabelSize = CGSizeMake(self.frame.size.width,9999);
    
    CGRect expectedLabelRect = [[self text] boundingRectWithSize:maximumLabelSize
                                                         options:(NSStringDrawingUsesLineFragmentOrigin | NSStringDrawingUsesFontLeading)
                                                      attributes:attributesDictionary
                                                         context:nil];
    CGSize *expectedLabelSize = &expectedLabelRect.size;
    
    return expectedLabelSize->height;
}

@end