如何根据内容调整UITextView的大小并固定宽度

Question

I have to create a UITextView programmatically, but I ran into some trouble about setting its size.

Suppose I have a sentence, with multiple lines:

s = @"Hello World\\nHello World\\nHello World\\n";

Now I want to figure out the height I need to display it, and set my UITextView's height accordingly (the width need to be fixed). Following is my code:

    CGSize size = [text sizeWithFont:_FONT_MYRIADPRO(20.0f) constrainedToSize:CGSizeMake(300, 1000)];

    _textBox.text = text;
    _textBox.frame = CGRectMake(10, 10, 300, size.height);
    _textBox.font = _FONT_MYRIADPRO(20.0f);
    _textBox.textColor = _COLOR_BLACK;
    _textBox.backgroundColor = _COLOR_BLUE_DARK;

    self.frame = CGRectMake(0, 0, 320, _textBox.frame.size.height + 2 * 10);

     [self addSubview:_textBox];

However, the result is like:

I have tried many other methods, like call

[_textBox sizeToFit]

which also fails, because I want to fix width.

I also tried

    NSAttributedString *titleText = [[NSAttributedString alloc] initWithString:text attributes:@{NSFontAttributeName: _FONT_MYRIADPRO(20.0f)}];
    CGRect bound = [titleText boundingRectWithSize:CGSizeMake(300, 1000) options:NSStringDrawingUsesLineFragmentOrigin context:nil];

    _textBox.text = text;
    _textBox.frame = CGRectMake(10, 10, 300, bound.size.height);

it also fails, and result is the same as the above image.

Could anyone help me?

Answer 1

I do some test for this case. I think we'd better add descender and leading for height. Please refer to https://developer.apple.com/library/ios/documentation/StringsTextFonts/Conceptual/TextAndWebiPhoneOS/Introduction/Introduction.html for the details of the meanings of descender and leading.

My sample code is as below:

//
//  RootViewController.m
//  TextViewSize
//
//  Created by AnkyHe on 11/13/13.
//  Copyright (c) 2013 Gery Studio. All rights reserved.
//
#import <QuartzCore/QuartzCore.h>

#import "RootViewController.h"

#define TextFont ([UIFont systemFontOfSize:20.0f])

static NSString *textContent = nil;
static NSUInteger const LineNum = 10;

@interface RootViewController ()

@property (nonatomic, weak)  UITextView *textView;

@end

@implementation RootViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
  // Do any additional setup after loading the view.

    NSMutableArray *lines = [[NSMutableArray alloc] initWithCapacity:LineNum];
    for (int i = 0; i < LineNum; ++i) {
        [lines addObject:[NSString stringWithFormat:@"%d Hello world", i]];
    }

    textContent = [lines componentsJoinedByString:@"\n"];

    self.view.backgroundColor = [UIColor whiteColor];

    UITextView *textView = [[UITextView alloc] init];
    self.textView = textView;
    self.textView.text = textContent;
    self.textView.font = TextFont;
    [self.view addSubview:self.textView];
}

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

- (void)viewDidLayoutSubviews
{
    [super viewDidLayoutSubviews];

    CGRect textRect = [textContent boundingRectWithSize:CGSizeMake(300, 1000)
                                                options:NSStringDrawingUsesLineFragmentOrigin
                                             attributes:@{NSFontAttributeName:TextFont}
                                                context:nil];

    CGSize size = textRect.size;
    self.textView.frame = CGRectMake(0, 0, 300, size.height + TextFont.descender + TextFont.leading);
    self.textView.center = CGPointMake(CGRectGetMidX(self.view.bounds), CGRectGetMidY(self.view.bounds));
}

@end

The output is as below: