iBooks App如何在单独的页面上格式化文本？

Question

看看iBooks应用程序,我想知道如何完成格式化文本(可能是一个非常简单的txt文件),这样它就不可滚动,而是分成不同的页面.

我想实现相同的目标,但只能使用可编辑的文本.

我需要从哪里开始？UITextView在滚动时不起作用.即使我将pagingEnabled属性设置为YES,它也不会执行该任务.

似乎我需要限制我可以放在某个页面上的文本数量.是否有一个限制UITextView输入的功能？我需要限制LINES(不是字符)的数量,因为它们将显示在完整的iPhone屏幕上(我猜你可以适应20行左右,具体取决于字体大小).

任何帮助,将不胜感激!由于我是初学者,我特别欣赏使用类似方法的样本.

谢谢!

Answer 1

您需要的是一个自己的布局算法，该算法获取文本，测量其大小并剪切它，直到它适合单页文本视图。然后从文本的其余部分开始，对于下一个文本视图也是如此......之后（或在算法内部）您将所有生成的文本视图排列在滚动视图上（或在数组中，稍后您可以翻转）带有分页动画 - 如果你喜欢它俗气的话）。我做了类似的事情，但是对于 UILabels，它也应该适用于文本视图。你需要的是：NSString's - (CGSize)sizeWithFont:(UIFont *)font constrainedToSize:(CGSize)size和 r angeOfString:@" " options:NSBackwardsSearch（寻找单词空间）和substringFromIndex: resp。substringToIndex:

如果您需要更多信息，请发表评论。

编辑：

您好，以下代码未经测试，但包含您需要的大部分内容（希望如此），但可能存在一些错误，特别是在递归方面......我纠正了 BackWardsSearch 的想法，因为它可能需要很长时间才能削减很长的时间文本。我完全忽略了——这可能真的很棘手——是编辑时重新渲染。但无论如何，这是代码。这是一个假设为老 4 成员的视图控制器（头文件未发布）：

  UIView *editableBook;
  NSMutableArray *content;
  int currentPage;
  UIFont *font;

这是控制器本身：

//
//  EditableBookController.m
//
//  Created by Kai on 09.03.11.
//

#import "EditableBookController.h"


@implementation EditableBookController

-(id)initWithText:(NSString *)text
{
  if (self=[super init]) 
  {
    font = [UIFont fontWithName:@"SomeFont" size:12];
    content = [[NSMutableArray alloc]init];
    [self cutInPages:text];
    currentPage = 0;  
  }
  return self;
}

- (void)loadView 
{
  self.view = [[UIView alloc] initWithFrame:CGRectMake(.0, .0, 768., 1024.)];//assuming portrait only ...
  editableBook = [[UIView alloc]initWithFrame:self.view.bounds];//could be a scroll view in alternate approach
  UISwipeGestureRecognizer *flipper = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(nextOrPrevious:)];
  [editableBook addGestureRecognizer:flipper];
  [flipper release];
  [self.view addSubview:editableBook];
  UITextView *textView = [[UITextView alloc]initWithText:[content objectAtIndex:currentPage]];
  textView.frame = editableBook.bounds;
  textView.font = font;
  textView.tag = 23;
  [editableBook addSubview:textView];
  [textView release];
}

-(void)nextOrPrevious:(id)sender
{
  UISwipeGestureRecognizer *flipper = (UISwipeGestureRecognizer*)sender;
  if(flipper.direction == UISwipeGestureRecognizerDirectionLeft)
  {
    [self next];
  }
  else if(flipper.direction == UISwipeGestureRecognizerDirectionRight)
  {
    [self previous];
  }
}

-(void)next
{
  if(currentPage == content.count - 1)
  {
    return;
  }
  currentPage++;
  UIView *fromView = [editableBook viewWithTag:23];
  UIView *toView =  [[UITextView alloc]initWithText:[content objectAtIndex:currentPage]];
  toView.frame = editableBook.bounds;
  toView.tag = 23;
  [UIView transitionWithView:editableBook duration:0.2 options:UIViewAnimationTransitionFlipFromRight
   animations:^
   {
     [fromView removeFromSuperview];
     [editableBook addSubview:toView];
   }
   completion:NULL];
}

-(void)previous
{
  if(currentPage == 0)
  {
    return;
  }
  currentPage--;
  UIView *fromView = [editableBook viewWithTag:23];
  UIView *toView =  [[UITextView alloc]initWithText:[content objectAtIndex:currentPage]];
  toView.frame = editableBook.bounds;
  toView.tag = 23;
  [UIView transitionWithView:editableBook duration:0.2 options:UIViewAnimationTransitionFlipFromLeft
   animations:^
   {
     [fromView removeFromSuperview];
     [editableBook addSubview:toView];
   }
   completion:NULL];
}

-(void)cutInPages:(NSString *)text
{
  NSRange whereToCut = whereToCut = [text rangeOfString:@" "];
  NSString *pageText = [text substringToIndex:whereToCut.location];
  NSString *rest = [text substringFromIndex:whereToCut.location];;
  CGFloat height = 0;
  while (height<1024.) 
  {
    NSRange whereToCut = [rest rangeOfString:@" "];
    NSString *wordOfRest = [rest substringToIndex:whereToCut.location];
    pageText = [NSString stringWithFormat:@"%@%@", pageText, wordOfRest];
    rest = [rest substringFromIndex:whereToCut.location];;
    CGSize size = [pageText sizeWithFont:font
                      constrainedToSize:CGSizeMake(768., 10000) 
                          lineBreakMode:UILineBreakModeWordWrap];
    height = size.height;
  }
  if(height>1024.)
  {
    //TODO cut the last word of pageText and prepend to the eest
  }
  [content addObject:pageText];
  if([rest length] > 0)
  {
    [self cutInPages:rest];
  }
}

- (void)dealloc 
{
  [editableBook release];
  [content release];
  [super dealloc];
}


@end