浅析NSTextContainer

- (void)viewDidLoad
{
    [super viewDidLoad];
    
    // 数据源
    NSString *string = [NSString stringWithContentsOfURL:[NSBundle.mainBundle URLForResource:@"bubizhidaowoshishui" withExtension:@"txt"] usedEncoding:nil
                                                   error:nil];
    
    // 文本容器
    NSTextStorage *storage = [[NSTextStorage alloc] initWithString:string];
    
    // 文本容器的布局管理器
    NSLayoutManager *layoutManager = [NSLayoutManager new];
    [storage addLayoutManager:layoutManager];
    
    // 分段显示文本容器中的内容
    CGSize size = CGSizeMake(300, 540);
    NSTextContainer *textContainer1 = [[NSTextContainer alloc] initWithSize:size];
    [layoutManager addTextContainer:textContainer1];
    NSTextContainer *textContainer2 = [[NSTextContainer alloc] initWithSize:size];
    [layoutManager addTextContainer:textContainer2];
    NSTextContainer *textContainer3 = [[NSTextContainer alloc] initWithSize:size];
    [layoutManager addTextContainer:textContainer3];
    NSTextContainer *textContainer4 = [[NSTextContainer alloc] initWithSize:size];
    [layoutManager addTextContainer:textContainer4];
    
    // 给TextView添加带有内容和布局的容器
    UITextView *textView = [[UITextView alloc] initWithFrame:CGRectMake(10, 20,
                                                                        size.width, size.height)
                                               textContainer:textContainer1];
    textView.layer.borderWidth = 1;
    textView.scrollEnabled     = NO;
    textView.editable          = NO;
    [self.view addSubview:textView];
    
    // 验证
    if (textView.textStorage == storage)
    {
        NSLog(@"textView.textStorage == storage");
    }
    
    if (textView.layoutManager == layoutManager)
    {
        NSLog(@"textView.layoutManager == layoutManager");
    }
    
    NSLog(@"计算的页码数:%f", [textView sizeThatFits:CGSizeMake(300, FLT_MAX)].height / 540.f);
}