评估 NSString 大小以填充 UITextView

Question

我有一个不可滚动的 UITextView，我想用文本动态填充这个框架。

这是我的课程代码：

#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

但如果在 applyText 函数中计算的文本高度小于框架的高度，则效果很好，否则测量的高度是错误的。

文本视图大小为 300x620

有什么想法吗？提前谢谢

Answer 1

如果我回答了我的问题，请原谅我，但我找到了解决方案，我认为它对于解决像我这样的问题很有用。

我在这篇文章中使用这个函数来评估正确的字体大小：

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;
    }
}

以及我在 applyText 函数中的这两行代码：

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

因为第一次UITextView的frame不正确。

感谢您的支持

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: 永远不会增加传入的大小。要准确测量所需的最小大小，请在调用之前将高度更改为某个较大的数字：

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