iOS文本布局探讨之一——文本布局框架TextKit浅析

    //定义Container
    NSTextContainer * container = [[NSTextContainer alloc]initWithSize:CGSizeMake(150, 200)];
    //定义布局管理类
    NSLayoutManager * layoutManager = [[NSLayoutManager  alloc]init];
    //将container添加进布局管理类管理
    [layoutManager addTextContainer:container];
    //定义一个Storage
    NSTextStorage * storage = [[NSTextStorage alloc]initWithString:@"The NSTextContainer class defines a region where text is laid out. An NSLayoutManager uses NSTextContainer to determine where to break lines, lay out portions of text, and so on."];
    //为Storage添加一个布局管理器
    [storage addLayoutManager:layoutManager];
    //将要显示的container与视图TextView绑定
    UITextView * textView = [[UITextView alloc]initWithFrame:self.view.frame textContainer:container];
    [self.view addSubview:textView];

//初始化方法 设置区块的尺寸
- (instancetype)initWithSize:(CGSize)size;
//与其绑定的layoutManager 需要注意，不是设置这个属性 使用[NSLayoutManager addTextContainer:]方式来进行绑定
@property(nullable, assign, NS_NONATOMIC_IOSONLY) NSLayoutManager *layoutManager;
//替换绑定的布局管理类对象
- (void)replaceLayoutManager:(NSLayoutManager *)newLayoutManager;
//获取区块尺寸
@property(NS_NONATOMIC_IOSONLY) CGSize size;
//设置从区块中剔除某一区域
@property(copy, NS_NONATOMIC_IOSONLY) NSArray<UIBezierPath *> *exclusionPaths;
//设置截断模式 需要注意 这个属性的设置只是会影响此区块的最后一行的截断模式
@property(NS_NONATOMIC_IOSONLY) NSLineBreakMode lineBreakMode;
//设置每行文本左右空出的间距
@property(NS_NONATOMIC_IOSONLY) CGFloat lineFragmentPadding;
//设置TextView上可输入的文本最大行数
@property(NS_NONATOMIC_IOSONLY) NSUInteger maximumNumberOfLines;

//这个方法用于提供给子类进行重写 这里返回的Rect是可以布局文本的区域
- (CGRect)lineFragmentRectForProposedRect:(CGRect)proposedRect atIndex:(NSUInteger)characterIndex writingDirection:(NSWritingDirection)baseWritingDirection remainingRect:(nullable CGRect *)remainingRect;
//这个BOOL值的属性决定Container的宽度是否自适应TextView的宽度
@property(NS_NONATOMIC_IOSONLY) BOOL widthTracksTextView;
//这个BOOL值的属性决定Container的高度是否自适应TextView的高度
@property(NS_NONATOMIC_IOSONLY) BOOL heightTracksTextView;

 [super viewDidLoad];
    NSTextContainer * container = [[NSTextContainer alloc]initWithSize:CGSizeMake(300, 500)];

    UIBezierPath * path = [UIBezierPath bezierPathWithArcCenter:self.view.center radius:70 startAngle:0 endAngle:M_PI*2 clockwise:YES];
    container.exclusionPaths = @[path];
    container.lineBreakMode = NSLineBreakByCharWrapping;
    NSLayoutManager * layoutManager = [[NSLayoutManager  alloc]init];
    [layoutManager addTextContainer:container];
    NSTextStorage * storage = [[NSTextStorage alloc]initWithString:@"The NSTextContainer class defines a region where text is laid out. An NSLayoutManager uses NSTextContainer to determine where to break lines, lay out portions of text, and so on. An NSTextContainer object normally defines rectangular regions, but you can define exclusion paths inside the text container to create regions where text does not flow. You can also subclass to create text containers with nonrectangular regions, such as circular regions, regions with holes in them, or regions that flow alongside graphics.The NSTextContainer class defines a region where text is laid out. An NSLayoutManager uses NSTextContainer to determine where to break lines, lay out portions of text, and so on. An NSTextContainer object normally defines rectangular regions, but you can define exclusion paths inside the text container to create regions where text does not flow. You can also subclass to create text containers with nonrectangular regions, such as circular regions, regions with holes in them, or regions that flow alongside graphics.An NSLayoutManager uses NSTextContainer to determine where to break lines, lay out portions of text, and so on. An NSTextContainer object normally defines rectangular regions, but you can define exclusion paths inside the text container to create regions where text does not flow. You can also subclass to create text containers with nonrectangular regions, such as circular regions, regions with holes in them, or regions that flow alongside graphics."];
    [storage addLayoutManager:layoutManager];
    UITextView * textView = [[UITextView alloc]initWithFrame:self.view.frame textContainer:container];
    [self.view addSubview:textView];

//container数组
@property(readonly, NS_NONATOMIC_IOSONLY) NSArray<NSTextContainer *> *textContainers;
//添加一个container
- (void)addTextContainer:(NSTextContainer *)container;
//在指定位置插入一个container
- (void)insertTextContainer:(NSTextContainer *)container atIndex:(NSUInteger)index;
//删除一个指定的container
- (void)removeTextContainerAtIndex:(NSUInteger)index;
//注意 这个方法不需要显式的调用 当布局Container发生变化时 系统会自动调用
- (void)textContainerChangedGeometry:(NSTextContainer *)container;

//是否显示隐形的符号
/*
默认为NO，如果设置为YES，则会将空格等隐形字符显示出来
*/
@property(NS_NONATOMIC_IOSONLY) BOOL showsInvisibleCharacters;
//是否显示某些布局控制字符
@property(NS_NONATOMIC_IOSONLY) BOOL showsControlCharacters;
//这个属性可以用于设置断字
/*
这个属性的取值为0到1之间 默认为0 即单词换行时从来不会中断 越接近1 则使用连字符进行单词换行中断的概率越大
*/
@property(NS_NONATOMIC_IOSONLY) CGFloat hyphenationFactor;
//是否使用字体定义的行距
/*
默认使用字体所定义的行距信息 通过设置这个属性为NO可以关闭此功能
*/
@property(NS_NONATOMIC_IOSONLY) BOOL usesFontLeading;
//这个属性设置是否允许对相邻位置的内容进行布局 默认为YES，设置为NO后将可以提供大文本布局的效率
@property(NS_NONATOMIC_IOSONLY) BOOL allowsNonContiguousLayout;

//下面这几个方法用于移除某一范围内的布局
- (void)invalidateGlyphsForCharacterRange:(NSRange)charRange changeInLength:(NSInteger)delta actualCharacterRange:(nullable NSRangePointer)actualCharRange;
- (void)invalidateLayoutForCharacterRange:(NSRange)charRange actualCharacterRange:(nullable NSRangePointer)actualCharRange NS_AVAILABLE(10_5, 7_0);
- (void)invalidateDisplayForCharacterRange:(NSRange)charRange;
- (void)invalidateDisplayForGlyphRange:(NSRange)glyphRange;