UITextView+Dimensions.h

//
//  UITextView+Dimensions.h
//
//  Created by Justin Driscoll on 1/6/12.
//

#import <UIKit/UIKit.h>

@interface UITextView (Dimensions)

+ (CGFloat)heightWithText:(NSString *)text font:(UIFont *)font atWidth:(CGFloat)width;

@end

UITextView+Dimensions.m

//
//  UITextView+Dimensions.m
//
//  Created by Justin Driscoll on 1/6/12.
//

#import "UITextView+Dimensions.h"


// This represents the total vertical and horizontal padding applied to the text.
// We have to subtract this from our original width and add it to the resulting
// height to get the correct dimensions.
static const CGFloat marginAdjustment = 16.0;


@implementation UITextView (Dimensions)

+ (CGFloat)heightWithText:(NSString *)text font:(UIFont *)font atWidth:(CGFloat)width
{
    CGSize bounds = CGSizeMake(width - marginAdjustment, CGFLOAT_MAX);
    
    CGSize size = [text sizeWithFont:font
                   constrainedToSize:bounds
                       lineBreakMode:NSLineBreakByWordWrapping];
    
    return size.height + marginAdjustment;
}

@end

update for ios 7?