textField.selectedTextRange = nil; // hides caret
参考资料
https://www.orcode.com/question/893161_k4af1d.html https://blog.csdn.net/zhanglizhi111/article/details/71411584
UITextField隐藏光标
原文：https://www.cnblogs.com/zhouhui231/p/14986508.html
