NSAttributeString使用介绍（含经常使用Attribute键值对照表）

###1、Attributes字典键值对照表

键	值类型	备注
NSKernAttributeName	NSNumber	文字间距，支持浮点型
NSFontAttributeName	UIFont	字体
NSForegroundColorAttributeName	UIColor	颜色
NSParagraphStyleAttributeName	NSMutableParagraphStyle	段落样式，详细见【1】
NSBackgroundColorAttributeName	UIColor	字体的所占区域的背景颜色
NSStrokeColorAttributeName	UIColor	字体边框的颜色
NSStrokeWidthAttribute	NSNumber	边框的宽度
NSStrikethroughStyleAttributeName	NSNumber	删除线
NSUnderlineStyleAttributeName	NSNumber	下划线
NSVerticalGlyphFormAttributeName	NSNumber	文字排版方向0 表示横排文本.1 表示竖排文本，iOS只有横排
NSObliquenessAttributeName	NSNumber	文字倾斜程度
NSExpansionAttributeName	NSNumber	文字的扁平化程度
NSShadowAttributeName	NSShadow	文字阴影，见【2】

【1】NSMutableParagraphStyle类使用范例

NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc] init];
paragraphStyle.lineSpacing = 10;// 字体的行间距
paragraphStyle.firstLineHeadIndent = 20.0f;//首行缩进
paragraphStyle.alignment = NSTextAlignmentJustified;//（两端对齐的）文本对齐方式：（左，中，右，两端对齐，天然）
paragraphStyle.lineBreakMode = NSLineBreakByTruncatingTail;//结尾部分的内容以……方式省略 ( "...wxyz" ,"abcd..." ,"ab...yz")
paragraphStyle.headIndent = 20;//总体缩进(首行除外)
paragraphStyle.tailIndent = 20;//尾部缩进
paragraphStyle.minimumLineHeight = 10;//最低行高
paragraphStyle.maximumLineHeight = 20;//最大行高
paragraphStyle.paragraphSpacing = 15;//段与段之间的间距
paragraphStyle.paragraphSpacingBefore = 22.0f;//段首行空白空间/* Distance between the bottom of the previous paragraph (or the end of its paragraphSpacing, if any) and the top of this paragraph. */paragraphStyle.baseWritingDirection = NSWritingDirectionLeftToRight;//从左到右的书写方向（一共➡️⬇️⬅️三种）
paragraphStyle.lineHeightMultiple = 15;/* Natural line height is multiplied by this factor (if positive) before being constrained by minimum and maximum line height. */
paragraphStyle.hyphenationFactor = 1;//连字属性 在iOS，惟一支持的值分别为0和1
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【2】NSShadowAttributeName对应的是NSShadow对象,单一使用不会有任何效果,须要配合着NSVerticalGlyphFormAttributeName(文字排版方向)、NSObliquenessAttributeName(文字倾斜)、NSExpansionAttributeName(文字扁平化)配合使用,NSShadow相关属性设置以下所示.

NSShadow *shadow = [[NSShadow alloc]init];
shadow.shadowBlurRadius = 5;//模糊度
shadow.shadowColor = [UIColor whiteColor];//阴影颜色
shadow.shadowOffset = CGSizeMake(1, 5);//阴影的大小
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2、 NSAttributedString与NSMutableAttributedString

1.NSAttributedString 属性

//均为只读
@property (readonly, copy) NSString *string;
@property (readonly) NSUInteger length;
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建立方法

- (instancetype)initWithString:(NSString *)str;
- (instancetype)initWithAttributedString:(NSAttributedString *)attrStr;
- (instancetype)initWithString:(NSString *)str attributes:(nullable NSDictionary<NSString *, id> *)attrs;
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其余方法

//富文本字符串比较
- (BOOL)isEqualToAttributedString:(NSAttributedString *)other;
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2.NSMutableAttributedString 做为NSAttributedString的子类增长了如下动态添加富文本样式的方法，见文思意，也没必要过多解释。

- (void)addAttribute:(NSString *)name value:(id)value range:(NSRange)range;
- (void)addAttributes:(NSDictionary<NSString *, id> *)attrs range:(NSRange)range;
- (void)removeAttribute:(NSString *)name range:(NSRange)range;
- (void)replaceCharactersInRange:(NSRange)range withAttributedString:(NSAttributedString *)attrString;
- (void)insertAttributedString:(NSAttributedString *)attrString atIndex:(NSUInteger)loc;
- (void)appendAttributedString:(NSAttributedString *)attrString;

//彻底替换掉attributeString的内容
- (void)setAttributedString:(NSAttributedString *)attrString;
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###3、demo 若是以上看完了，还不懂怎么使用的朋友。那不妨看看在下拙劣的demo吧。(注：Label的背景颜色都是在xib（nib）中设置的)

• 文字间距

  

NSAttributedString *string = [[NSAttributedString alloc] initWithString:@"改变文字间距,间距为6"attributes:@{NSKernAttributeName:@6}];
    _label1.attributedText = string;
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• 字体

NSAttributedString *string = [[NSAttributedString alloc] initWithString:@"改变文字字体,20号粗体"attributes:@{NSFontAttributeName:[UIFont boldSystemFontOfSize:20]}];
    _label2.attributedText = string;
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• 颜色

NSAttributedString *string = [[NSAttributedString alloc] initWithString:@"改变文字颜色,绿色"attributes:@{NSForegroundColorAttributeName:[UIColor greenColor]}];
    _label3.attributedText = string;
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• 描边和空心

NSMutableAttributedString *mutableAttributedstring = [[NSMutableAttributedString alloc] initWithString:@"改变文字边框颜色宽度,这二者协同使用才有效果，宽度正数为空心（前景色失效），负数描边"];
    //空心
    [mutableAttributedstring addAttribute:NSStrokeWidthAttributeName value:@3.2 range:NSMakeRange(0, 37)];
    [mutableAttributedstring addAttribute:NSStrokeColorAttributeName value:[UIColor greenColor] range:NSMakeRange(0, 37)];
    
    //描边
    [mutableAttributedstring addAttribute:NSStrokeWidthAttributeName value:@-5 range:NSMakeRange(38, mutableAttributedstring.length - 38)];
    [mutableAttributedstring addAttribute:NSStrokeColorAttributeName value:[UIColor redColor] range:NSMakeRange(38, mutableAttributedstring.length - 38)];
    _label4.numberOfLines = 3;
    _label4.attributedText = mutableAttributedstring;

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• 删除线

NSMutableAttributedString *mutableAttributedstring = [[NSMutableAttributedString alloc] initWithString:@"一条删除线，两条删除线，加粗删除线"];
    [mutableAttributedstring addAttribute:NSStrikethroughStyleAttributeName value:[NSNumber numberWithInteger:NSUnderlineStyleSingle] range:NSMakeRange(0,5)];
    [mutableAttributedstring addAttribute:NSStrikethroughStyleAttributeName value:[NSNumber numberWithInteger:NSUnderlineStyleDouble] range:NSMakeRange(6,5)];
    [mutableAttributedstring addAttribute:NSStrikethroughStyleAttributeName value:[NSNumber numberWithInteger:NSUnderlineStyleThick] range:NSMakeRange(12,5)];
    _label5.attributedText = mutableAttributedstring;
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• 下划线

NSMutableAttributedString *mutableAttributedstring = [[NSMutableAttributedString alloc] initWithString:@"一条下划线，两条下划线，加粗下划线"];
    [mutableAttributedstring addAttribute:NSUnderlineStyleAttributeName value:[NSNumber numberWithInteger:NSUnderlineStyleSingle] range:NSMakeRange(0,5)];
    [mutableAttributedstring addAttribute:NSUnderlineStyleAttributeName value:[NSNumber numberWithInteger:NSUnderlineStyleDouble] range:NSMakeRange(6,5)];
    [mutableAttributedstring addAttribute:NSUnderlineStyleAttributeName value:[NSNumber numberWithInteger:NSUnderlineStyleThick] range:NSMakeRange(12,5)];
    _label6.attributedText = mutableAttributedstring;
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• 斜体、阴影和压扁

NSMutableAttributedString *mutableAttributedstring = [[NSMutableAttributedString alloc] initWithString:@"文字倾斜，文字阴影，压扁文字"];
    [mutableAttributedstring addAttribute:NSObliquenessAttributeName value:@1 range:NSMakeRange(0,4)];
    
    //文字阴影
    NSShadow *shadow = [[NSShadow alloc] init];
    //模糊度
    shadow.shadowBlurRadius = 5;
    //阴影颜色
    shadow.shadowColor = [UIColor yellowColor];
    //阴影大小
    shadow.shadowOffset = CGSizeMake(2, 5);
    [mutableAttributedstring addAttribute:NSShadowAttributeName value:shadow range:NSMakeRange(5,4)];
    
    //压扁文字
    [mutableAttributedstring addAttribute:NSExpansionAttributeName value:@0.8 range:NSMakeRange(10,4)];
    _label7.numberOfLines = 2;
     _label7.attributedText = mutableAttributedstring;
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• 段落样式

NSMutableAttributedString *mutableAttributedstring = [[NSMutableAttributedString alloc] initWithString:@"据外媒报道，美国太空探索技术公司SpaceX原定于北京时间2月18日23时01分，在佛罗里达州发射“龙”无人货运飞船，运送补给物资前往国际太空站，并尝试回收搭载飞船的“猎鹰9”号火箭。但二级火箭在倒计时13秒时因引擎故障，宣布取消发射。\n在发射暂停后约10分钟后，SpaceX首席执行官埃隆·马斯克(Elon Musk)在社交媒体上发布消息称：“一切运行正常，除了二级火箭发动机转向液压活塞的运动轨迹稍显奇怪，须要进行调查。”"];
    
    NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc] init];
    // 字体的行间距
    paragraphStyle.lineSpacing = 10;
    //首行缩进
    paragraphStyle.firstLineHeadIndent = 20.0f;
    //（两端对齐的）文本对齐方式：（左，中，右，两端对齐，天然）
//    paragraphStyle.alignment = NSTextAlignmentLeft;
    //结尾部分的内容以……方式省略 ( "...wxyz" ,"abcd..." ,"ab...yz")
//    paragraphStyle.lineBreakMode = NSLineBreakByTruncatingTail;
    paragraphStyle.headIndent = 20;//总体缩进(首行除外)
    //设置尾部缩进后就出问题
//    paragraphStyle.tailIndent = 2;//尾部缩进
    paragraphStyle.minimumLineHeight = 10;//最低行高
    paragraphStyle.maximumLineHeight = 20;//最大行高
//    paragraphStyle.paragraphSpacing = 15;//段与段之间的间距
    paragraphStyle.paragraphSpacingBefore = 22.0f;//段首行空白空间/* Distance between the bottom of the previous paragraph (or the end of its paragraphSpacing, if any) and the top of this paragraph. */
    paragraphStyle.baseWritingDirection = NSWritingDirectionLeftToRight;//从左到右的书写方向（一共➡️⬇️⬅️三种）
    
    paragraphStyle.lineHeightMultiple = 15;/* Natural line height is multiplied by this factor (if positive) before being constrained by minimum and maximum line height. */
    paragraphStyle.hyphenationFactor = 1;//连字属性 在iOS，惟一支持的值分别为0和1
    [mutableAttributedstring addAttribute:NSParagraphStyleAttributeName value:paragraphStyle range:NSMakeRange(0, mutableAttributedstring.length)];
    [mutableAttributedstring addAttribute:NSFontAttributeName value:[UIFont systemFontOfSize:10] range:NSMakeRange(0, mutableAttributedstring.length)];
    _label8.numberOfLines = MAXFLOAT;
    _label8.attributedText = mutableAttributedstring;
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经常使用的也就这些了吧，更深刻仍是用富文本框架吧。