NSLineBreakByWordWrapping = 0, // Wrap at word boundaries, default 以空格为边界保留单词
NSLineBreakByCharWrapping, // Wrap at character boundaries 保留整个字符
NSLineBreakByClipping, // Simply clip 简单截取，截去多余部分
NSLineBreakByTruncatingHead, // Truncate at head of line: "...wxyz" 截去头部
NSLineBreakByTruncatingTail, // Truncate at tail of line: "abcd..." 截去尾部
NSLineBreakByTruncatingMiddle 截去中间
设置字体大小是否适应Label宽度
label.adjustFontSizeToFitWidth = YES;
设置高亮
label.highlighted = YES
设置高亮颜色
label.highlghtedTextColor = [UIColor greenColor];
设置阴影颜色
label.shaowColor = [UIColor blackColor];
设置阴影偏移量
label.shaowOffSet = CGSizeMake(x, y);
设置能否和用户进行交互
label.userInteractionEnabel = YES;
文字是否可变 默认YES
label.enabled = YES;
UIBaselineAdjustmentAlignBaselines 默认文本最上端与label中线对齐
UIBaselineAdjustmentAlignCenters text中间与label中线对齐
UIBaselineAdjustmentNone text底部与label中线对齐