evaluating NSString size to fill UITextView

Question

i have a not scrollable UITextView and i want fill this frame with text dynamically.

This is my class code:

#import "ViewController.h"

#define FONT_SIZE 17.0f

@interface ViewController ()<UITextViewDelegate>

@property (nonatomic, weak) IBOutlet UITextView * textview;
-(IBAction)changeText:(UIButton*)sender;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    self.automaticallyAdjustsScrollViewInsets = NO;

    NSString * plainText = @"Lorem ipsum dolor sit er elit lamet, consectetaur cillium adipisicing pecu, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum. Nam liber te conscient to factor tum poen legum odioque civiuda.Lorem ipsum dolor sit er elit lamet, consectetaur cillium adipisicing pecu, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum. Nam liber te conscient to factor tum poen legum odioque civiuda.Lorem ipsum dolor sit er elit lamet, consectetaur cillium adipisicing pecu, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum. Nam liber te conscient to factor tum poen legum odioque civiuda.Lorem ipsum dolor sit er elit lamet, consectetaur cillium adipisicing pecu, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum. Nam liber te conscient to factor tum poen legum odioque civiuda.Lorem ipsum dolor sit er elit lamet, consectetaur cillium adipisicing pecu, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum. Nam liber te conscient to factor tum poen legum odioque civiuda.Lorem ipsum dolor sit er elit lamet, consectetaur cillium adipisicing pecu, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum. Nam liber te conscient to factor tum poen legum odioque civiuda.Lorem ipsum dolor sit er elit lamet, consectetaur cillium adipisicing pecu, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum. Nam liber te conscient to factor tum poen legum odioque civiuda.Lorem ipsum dolor sit er elit lamet, consectetaur cillium adipisicing pecu, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum. Nam liber te conscient to factor tum poen legum odioque civiuda.";

    [self applyText:plainText];
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.

}

- (void)applyText: (NSString*) plainText
{
    self.textview.frame = CGRectMake(0,0,self.view.frame.size.width,self.view.frame.size.height-47);
    self.textview.contentSize = self.textview.frame.size;

    self.textview.attributedText = [[NSAttributedString alloc] initWithString:plainText];
    [self.textview setFont:[UIFont fontWithName:@"HelveticaNeue" size:FONT_SIZE]];
    [self.textview setTextAlignment:NSTextAlignmentCenter];


    //first method
    CGSize maximumLabelSize = self.textview.frame.size;
    maximumLabelSize.height = 9999;
    CGSize expectSize = [self.textview sizeThatFits:maximumLabelSize];

    NSLog(@"expected height %f",expectSize.height);

    //second method
    expectSize = [plainText boundingRectWithSize:CGSizeMake(self.textview.frame.size.width,MAXFLOAT) options:NSStringDrawingUsesLineFragmentOrigin attributes:@{NSFontAttributeName:self.textview.font} context:nil].size;

    NSLog(@"expected height 2 %f",expectSize.height);

    //third method
    expectSize = [self attributedSizeWithFont:self.textview.font maxWidth:self.textview.frame.size.width string:plainText];

    NSLog(@"expected height 3 %f",expectSize.height);



    if (expectSize.height <= self.textview.frame.size.height) {

        float fontSize = (FONT_SIZE * expectSize.height)/self.textview.frame.size.height;
        NSLog(@">> font: %.2f",fontSize);

        [self.textview setFont:[UIFont fontWithName:@"HelveticaNeue" size:fontSize]];

    }
    else if (expectSize.height > self.textview.frame.size.height) {

        float fontSize = (FONT_SIZE * self.textview.frame.size.height)/expectSize.height;

        NSLog(@"<< font: %.2f",fontSize);

        [self.textview setFont:[UIFont fontWithName:@"HelveticaNeue" size:fontSize]];

     }
}


- (CGSize) attributedSizeWithFont:(UIFont*) font maxWidth:(CGFloat) width string:(NSString*) string{

    NSMutableParagraphStyle* style = [[NSMutableParagraphStyle alloc] init];
    style.lineBreakMode = NSLineBreakByWordWrapping;
    NSAttributedString *attributedText = [[NSAttributedString alloc] initWithString:string
                                                                         attributes:@{ NSFontAttributeName:font,
                                                                                       NSForegroundColorAttributeName:[UIColor blackColor],
                                                                                       NSParagraphStyleAttributeName:style }];

    CGRect textRect = [attributedText boundingRectWithSize:CGSizeMake(width, MAXFLOAT)
                                                   options:(NSStringDrawingUsesLineFragmentOrigin)
                                                   context:nil];
    CGSize size = textRect.size;
    size.height = ceilf(size.height);
    size.width  = ceilf(size.width);

    return size;
}


-(IBAction)changeText:(UIButton*)sender
{
    NSString * plainText = @"Lorem ipsum dolor sit er elit lamet, consectetaur cillium adipisicing pecu, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum. Nam liber te conscient to factor tum poen legum odioque civiuda.Lorem ipsum dolor sit er elit lamet, consectetaur cillium adipisicing pecu, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum. Nam liber te conscient to factor tum poen legum odioque civiuda.Lorem ipsum dolor sit er elit lamet, consectetaur cillium adipisicing pecu, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.";

    [self applyText:plainText];

}
@end

but if the text height evaluated in applyText function is less than height of the frame, it works well otherwise the height measured is wrong.

the textview size is 300x620

any idea? thank's in advance

Answer 1

forgive me if I answer to my question, but I found the solution and I think it can be useful for solving problems like mine.

i use this function in this post for evaluating the correct font size:

Resize font size to fill UITextView?

- (void)updateTextFont:(UITextView *)textView
{
    // Only run if has text, otherwise it will make infinity loop
    if (textView.text.length == 0 || CGSizeEqualToSize(textView.bounds.size, CGSizeZero)) return;

    /*
     - Update textView font size
     If expectHeight > textViewHeight => descrease font size n point until it reach textViewHeight
     If expectHeight < textViewHeight => inscrease font size n point until it reach textViewHeight
     */
    CGSize textViewSize = textView.frame.size;
    CGFloat fixedWidth = textViewSize.width;
    CGSize expectSize = [textView sizeThatFits:CGSizeMake(fixedWidth, MAXFLOAT)];

    UIFont *expectFont = textView.font;
    if (expectSize.height > textViewSize.height) {
        while ([textView sizeThatFits:CGSizeMake(fixedWidth, MAXFLOAT)].height > textViewSize.height) {
            expectFont = [textView.font fontWithSize:(textView.font.pointSize - 0.5)];
            textView.font = expectFont;
        }
    } else {
        while ([textView sizeThatFits:CGSizeMake(fixedWidth, MAXFLOAT)].height < textViewSize.height) {
            expectFont = textView.font;
            textView.font = [textView.font fontWithSize:(textView.font.pointSize + 0.5)];
        }
        textView.font = expectFont;
    }
}

and this two lines of code that i have in applyText function:

self.textview.frame = CGRectMake(0,0,self.view.frame.size.width,self.view.frame.size.height-47);
    self.textview.contentSize = self.textview.frame.size;

because on the first time the frame of UITextView is incorrect.

thank's for your support

Answer 2

UITextView* dummyTextView = [[[UITextView alloc] initWithFrame:  self.textView.frame] autorelease];

dummyTextView.attributedText = [[NSAttributedString alloc] initWithString:plainText];
[dummyTextView.attributedText setFont:[UIFont fontWithName:@"HelveticaNeue" size:FONT_SIZE]];
[dummyTextView.attributedText setTextAlignment:NSTextAlignmentCenter];
[dummyTextView sizeToFit];
CGFloat expectedHeight = dummyTextView.bound.size.height;

Answer 3

sizeThatFits: never increases the size that's passed in. To accurately measure the minimum size that would be required, change the height to some large number before it's called:

CGSize maximumLabelSize = self.textview.frame.size;
maximumLabelSize.height = 9999.
CGSize expectSize = [self.textview sizeThatFits:maximumLabelSize];