Dynamically add mobile number

Hii, Klaus34
you can try this

a!localVariables(
  local!npi:{
    {
      mobileNo:""
    }
  },
  a!columnsLayout(
    columns:{
      a!columnLayout(
        contents: a!forEach(
          items: local!npi,
          expression:  a!textField(
            label: "Mobile Number",
            labelPosition: "ABOVE",
            value: fv!item.mobileNo,
            saveInto: fv!item.mobileNo,
            validations: if(
              a!isNullOrEmpty(fv!item.mobileNo),
              {},
              if(
                not(
                  regexmatch("^([0-9]{" & 10 & "})$", fv!item.mobileNo)
                ),
                "Maximum " & 10 & " digits are allowed",
                ""
              )
            )
          )
        )
      ),
      a!columnLayout(
        contents: a!linkField(
          label: "",
          links: {
            a!dynamicLink(
              label: "add new ",
              value: {
                mobileNo:""
              },
              saveInto: a!save(local!npi,append(local!npi,save!value))
            )
          }
        )
      )
    }
  )
)

thanks it helped .. can we do by comma separated in one text field only ??

Like this 1234567890, 1234567890 with validation  of 10 digits .. while saving i will iterate by a! for each

no, in one text field, you cannot add multiple numbers, but you can do it by using a text field  in side by side layout,

a!localVariables(
  local!npi:{
    {
      mobileNo:""
    }
  },
  a!sideBySideLayout(
    items: {
      a!forEach(
        items: local!npi,
        expression: a!sideBySideItem(
          item: a!textField(
            label: "Mobile Number",
            labelPosition: "ABOVE",
            value: fv!item.mobileNo,
            saveInto: fv!item.mobileNo,
            validations: if(
              a!isNullOrEmpty(fv!item.mobileNo),
              {},
              if(
                not(
                  regexmatch("^([0-9]{" & 10 & "})$", fv!item.mobileNo)
                ),
                "Maximum " & 10 & " digits are allowed",
                ""
              )
            )
          )
        )
      ),
      a!sideBySideItem(
        item: a!linkField(
          label: "",
          links: {
            a!dynamicLink(
              label: "add new ",
              value: {
                mobileNo:""
              },
              saveInto: a!save(local!npi,append(local!npi,save!value))
            )
          }
        )
      )
    }
  )
)

Following page has the details on what you are looking for - 

https://docs.appian.com/suite/help/22.4/recipe-add-multiple-text-components-dynamically.html