CATextLayer *textLayer = [CATextLayerlayer];
    textLayer.frame =CGRectMake(100,100,100,100);
    [self.view.layeraddSublayer:textLayer];
   
    textLayer.foregroundColor = [UIColorblackColor].CGColor;
    textLayer.alignmentMode =kCAAlignmentJustified;
    textLayer.wrapped =YES;
   
    UIFont *font = [UIFontsystemFontOfSize:15];
   
    CFStringRef fontName = (__bridgeCFStringRef)font.fontName;
    CGFontRef fontRef =CGFontCreateWithFontName(fontName);
    textLayer.font = fontRef;
    textLayer.fontSize = font.pointSize;
    CGFontRelease(fontRef);
   
    NSString *text =@"Cupid laid by his brand, and fell asleep";
   
    textLayer.string = text;

    textLayer.contentsScale = [UIScreen mainScreen].scale; // 在Retina显示