UILabel category to resize the frame height according to content text.

UILabel+Resize.h

@interface UILabel (Resize)

- (void)resizeToFit;

@end

UILabel+Resize.m

#import "UILabel+Resize.h"

@implementation UILabel (Resize)

- (void)resizeToFit
{
    CGFloat expectedHeight = [self expectedHeight];
    
    CGRect newFrame = self.frame;
    newFrame.size.height = expectedHeight;
    
    [self setFrame:newFrame];
}

- (CGFloat)expectedHeight
{
    [self setNumberOfLines:0];
    
    CGSize expectedLabelSize = [self.text sizeWithFont:self.font constrainedToSize:CGSizeMake(self.frame.size.width,9999) lineBreakMode:NSLineBreakByWordWrapping];
    
    return expectedLabelSize.height;
}

@end