给button增加下划线

如何给button增加下划线简单版

 

- (void)setunderlineforbutton:(uibutton *)btn withtitle:(nsstring *)title{

    //利用富文本的方式增加button下划线

    nsmutableattributedstring *str = [[nsmutableattributedstring alloc]initwithstring:title];

    nsrange strrange = {0,[str length]};

    [str addattribute:nsunderlinestyleattributename value:[nsnumber numberwithinteger:nsunderlinestylesingle] range:strrange];

    [btn setattributedtitle:str forstate:uicontrolstatenormal];

}