小说阅读器的设计和实现

  CGPoint insertPoint;
  CTFrameGetLineOrigins(frameRef, CFRangeMake(insertLineIndex + 1, 1), &insertPoint);

static CGFloat ascentCallback(void * refCon){
    SSEmptyLayoutData *data = (__bridge SSEmptyLayoutData *)refCon;
    return data.size.height;
}

static CGFloat descentCallback(void * refCon){
    return 50;
}

static CGFloat widthCallback(void * refCon){
    SSEmptyLayoutData *data = (__bridge SSEmptyLayoutData *)refCon;
    return data.size.width;
}

(lldb) bt
* thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0x7a0090020)
    frame #0: 0x0000000111350faa libobjc.A.dylib`objc_retain + 10
  * frame #1: 0x000000010a4fc566 TTReading`ascentCallback(ref=0x0000600003592e40) at SSLayoutManager.m:14
    frame #2: 0x000000010e5551a6 CoreText`TDelegateRun::TDelegateRun(CTRun const*) + 102
    frame #3: 0x000000010e4a03b6 CoreText`TGlyphEncoder::EncodeChars(CFRange, TAttributes const&, TGlyphEncoder::Fallbacks) + 518
    frame #4: 0x000000010e4b8b2a CoreText`TTypesetterAttrString::Initialize(__CFAttributedString const*) + 238
    frame #5: 0x000000010e4b8a2e CoreText`TTypesetterAttrString::TTypesetterAttrString(__CFAttributedString const*, __CFDictionary const*) + 176
    frame #6: 0x000000010e4b4422 CoreText`CTFramesetterCreateWithAttributedString + 91

CTRunDelegateRef delegate = CTRunDelegateCreate(&callbacks, (__bridge void *)(dict));   // Crash

CTRunDelegateRef delegate = CTRunDelegateCreate(&callbacks, (__bridge void *)(@"height"));   // OK

/**
 *  html字符串转富文本
 */
- (NSAttributedString *)htmlStrConvertToAttributeStr:(NSString *)htmlStr {
    return [[NSAttributedString alloc] initWithData:[htmlStr dataUsingEncoding:NSUnicodeStringEncoding]
                                            options:@{NSDocumentTypeDocumentAttribute:NSHTMLTextDocumentType}
                                 documentAttributes:nil
                                              error:nil];
}

(
    "NSRange: {0, 34}",
    "NSRange: {34, 36}",
    "NSRange: {70, 40}",
    "NSRange: {110, 39}",
    "NSRange: {149, 35}",
    "NSRange: {184, 40}",
    "NSRange: {224, 37}",
    "NSRange: {261, 38}",
    "NSRange: {299, 3}"
)

- (NSArray *)pagingContentWithAttributeStr:(NSAttributedString *)attributeStr pageSize:(CGSize)pageSize {
    NSMutableArray<NSValue *> *resultRange = [NSMutableArray array]; // 返回结果数组
    CGRect rect = CGRectMake(0, 0, pageSize.width, pageSize.height); // 每页的显示区域大小
    NSUInteger curIndex = 0; // 分页起点，初始为第0个字符
    while (curIndex < attributeStr.length) { // 没有超过最后的字符串，表明至少剩余一个字符
        NSUInteger maxLength = MIN(1000, attributeStr.length - curIndex); // 1000为最小字体的每页最大数量，减少计算量
        NSAttributedString * subString = [attributeStr attributedSubstringFromRange:NSMakeRange(curIndex, maxLength)]; // 截取字符串
        CTFramesetterRef frameSetter = CTFramesetterCreateWithAttributedString((__bridge CFAttributedStringRef) subString); // 根据富文本创建排版类CTFramesetterRef
        UIBezierPath * bezierPath = [UIBezierPath bezierPathWithRect:rect];
        CTFrameRef frameRef = CTFramesetterCreateFrame(frameSetter, CFRangeMake(0, 0), bezierPath.CGPath, NULL); // 创建排版数据，第个参数的range.length=0表示放字符直到区域填满
        CFRange visiableRange = CTFrameGetVisibleStringRange(frameRef); // 获取当前可见的字符串区域
        NSRange realRange = {curIndex, visiableRange.length}; // 当页在原始字符串中的区域
        [resultRange addObject:[NSValue valueWithRange:realRange]]; // 记录当页结果
        curIndex += realRange.length; //增加索引
        CFRelease(frameRef);
        CFRelease(frameSetter);
    };
    return resultRange;
}

if (curIndex > 0 && [attributeStr.string characterAtIndex:curIndex - 1] != '\n') {
    NSMutableParagraphStyle *style = [attributeStr attribute:NSParagraphStyleAttributeName atIndex:curIndex effectiveRange:NULL];
    NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc] init];
    paragraphStyle.firstLineHeadIndent = 0;
    paragraphStyle.lineBreakMode = NSLineBreakByCharWrapping;
    paragraphStyle.lineSpacing = style.lineSpacing;
    paragraphStyle.paragraphSpacing = style.paragraphSpacing;
    paragraphStyle.alignment = NSTextAlignmentJustified;
    [attributeStr addAttribute:NSParagraphStyleAttributeName value:paragraphStyle range:NSMakeRange(curIndex, 1)];
}

                CFRange range = CTLineGetStringRange(line);
                NSUInteger insertIndex = curIndex + range.location + range.length;
                if (insertIndex >= attributeStr.length) { // 避免最后一行的特殊情况处理
                    [attributeStr insertAttributedString:[[NSAttributedString alloc] initWithString:@"\n"] atIndex:insertIndex];
                    insertIndex = attributeStr.length;
                }

- (void)pageViewController:(UIPageViewController *)pageViewController didFinishAnimating:(BOOL)finished previousViewControllers:(NSArray<UIViewController *> *)previousViewControllers transitionCompleted:(BOOL)completed {
    if (!completed && previousViewControllers && [previousViewControllers[0] isKindOfClass:[SSReadingBasePageViewController class]]) {
        SSPageControllData *lastData = [(SSReadingBasePageViewController *)previousViewControllers[0] pageControllData];
        SSPageControllData *pageData = [self.pageControllManager onLoadingReadyWithChapterId:loadingVC.pageControllData.loadingData.loadingChapterId loadingData:loadingVC.pageControllData.loadingData];
        [self setPageVCWithPageControllData:pageData isNext:YES];
    }