根据内容的大小获得控件的大小

//宽度,高度,和字体大小
CGSize size = [contentString boundingRectWithSize:CGSizeMake(width, MAXFLOAT) options:NSStringDrawingUsesLineFragmentOrigin attributes:@{NSFontAttributeName:[UIFont boldSystemFontOfSize:16.0]} context:nil].size;