Unity/UIInputField

入力欄に文字列を入れる

GameObject objtext = GameObject.Find ("Canvas/InputField");
objtext.GetComponent<InputField> ().text = name;

入力欄に文字列を取得

GameObject objtext = GameObject.Find ("Canvas/InputField");
Debug.Log(objtext.GetComponent<InputField> ().text);

or

GameObject objtext = GameObject.Find ("Canvas/InputField/Text");
Debug.Log(objtext.GetComponent<Text> ().text);

数字のみに限定する

GameObject objtext = GameObject.Find("Canvas/InputField");
objtext.GetComponent<InputField>().contentType = InputField.ContentType.IntegerNumber;

参考

InputField公式：https://docs.unity3d.com/ja/530/Manual/script-InputField.html