IOS中CATextLayer绘制文本字符串

// 绘制文本的图层 
CATextLayer *layerText = [[CATextLayer alloc] init]; 
// 背景颜色 
layerText.backgroundColor = [UIColor orangeColor].CGColor; 
// 渲染分辨率-重要，否则显示模糊 
layerText.contentsScale = [UIScreen mainScreen].scale; 
// 显示位置 
layerText.bounds = CGRectMake(0.0, 0.0, 100.0, 50.0); 
layerText.position = position; 
// 添加到父图书 
[self.view.layer addSublayer:layerText]; 

// 分行显示 
layerText.wrapped = YES; 
// 超长显示时，省略号位置 
layerText.truncationMode = kCATruncationNone; 
// 字体颜色 
layerText.foregroundColor = [UIColor purpleColor].CGColor; 
// 字体名称、大小 
UIFont *font = [UIFont systemFontOfSize:15.0]; 
CFStringRef fontName = (__bridge CFStringRef)font.fontName; 
CGFontRef fontRef =CGFontCreateWithFontName(fontName); 
layerText.font = fontRef; 
layerText.fontSize = font.pointSize; 
CGFontRelease(fontRef); 
// 字体对方方式 
layerText.alignmentMode = kCAAlignmentJustified; 

// 字符显示 
NSString *text = @"devZhang is iOSDeveloper.devZhang is iOSDeveloper.devZhang is iOSDeveloper.devZhang is iOSDeveloper."; 

// 方法1-简单显示 
layerText.string = text; 

// 方法2-富文本显示 
// 文本段落样式 
NSMutableParagraphStyle *textStyle = [[NSMutableParagraphStyle alloc] init]; 
textStyle.lineBreakMode = NSLineBreakByWordWrapping; // 结尾部分的内容以……方式省略 ( "...wxyz" ,"abcd..." ,"ab...yz") 
textStyle.alignment = NSTextAlignmentCenter; //（两端对齐的）文本对齐方式：（左，中，右，两端对齐，自然） 
textStyle.lineSpacing = 5; // 字体的行间距 
textStyle.firstLineHeadIndent = 5.0; // 首行缩进 
textStyle.headIndent = 0.0; // 整体缩进(首行除外) 
textStyle.tailIndent = 0.0; // 
textStyle.minimumLineHeight = 20.0; // 最低行高 
textStyle.maximumLineHeight = 20.0; // 最大行高 
textStyle.paragraphSpacing = 15; // 段与段之间的间距 
textStyle.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. */ 
textStyle.baseWritingDirection = NSWritingDirectionLeftToRight; // 从左到右的书写方向（一共➡️三种） 
textStyle.lineHeightMultiple = 15; /* Natural line height is multiplied by this factor (if positive) before being constrained by minimum and maximum line height. */ 
textStyle.hyphenationFactor = 1; //连字属性 在iOS，唯一支持的值分别为0和1 
// 文本属性 
NSMutableDictionary *textAttributes = [[NSMutableDictionary alloc] init]; 
// NSParagraphStyleAttributeName 段落样式 
[textAttributes setValue:textStyle forKey:NSParagraphStyleAttributeName]; 
// NSFontAttributeName 字体名称和大小 
[textAttributes setValue:[UIFont systemFontOfSize:12.0] forKey:NSFontAttributeName]; 
// NSForegroundColorAttributeNam 颜色 
[textAttributes setValue:[UIColor greenColor] forKey:NSForegroundColorAttributeName]; 
NSMutableAttributedString *attributedText = [[NSMutableAttributedString alloc] initWithString:text]; 
[attributedText setAttributes:textAttributes range:NSMakeRange(0, 8)]; 
layerText.string = attributedText;