Tip: 参考文档：http://blog.csdn.net/reylen/article/details/21012859
@property(nonatomic) NSLineBreakMode lineBreakMode; // default is NSLineBreakByTruncatingTail. used for single and multiple lines of text
lineBreakMode：设置标签文字过长时的显示方式。
// NSParagraphStyle
typedef NS_ENUM(NSInteger, NSLineBreakMode) {
NSLineBreakByWordWrapping = , // Wrap at word boundaries, default
NSLineBreakByCharWrapping, // Wrap at character boundaries
NSLineBreakByClipping, // Simply clip
NSLineBreakByTruncatingHead, // Truncate at head of line: "...wxyz"
NSLineBreakByTruncatingTail, // Truncate at tail of line: "abcd..."
NSLineBreakByTruncatingMiddle // Truncate middle of line: "ab...yz"
} NS_ENUM_AVAILABLE(10_0, 6_0);
// NSParagraphStyle
typedef NS_ENUM(NSInteger, NSLineBreakMode) {
NSLineBreakByWordWrapping = , // Wrap at word boundaries, default 以单词为显示单位显示，后面部分省略不显示。
NSLineBreakByCharWrapping, // Wrap at character boundaries 以字符为显示单位显示，后面部分省略不显示
NSLineBreakByClipping, // Simply clip 剪切与文本宽度相同的内容长度，后半部分被删除。
NSLineBreakByTruncatingHead, // Truncate at head of line: "...wxyz" 前面部分文字以……方式省略，显示尾部文字内容。
NSLineBreakByTruncatingTail, // Truncate at tail of line: "abcd..." 结尾部分的内容以……方式省略，显示头的文字内容。
NSLineBreakByTruncatingMiddle // Truncate middle of line: "ab...yz" 中间的内容以……方式省略，显示头尾的文字内容。
} NS_ENUM_AVAILABLE(10_0, 6_0);