customComponents.js

const CustomTextInput = ({ placeholder, input, meta, label }) => (
  <View style={styles.container}>
    {label && <Text style={styles.labelTitle}>{label}</Text>}
    <TextInput style={styles.textInput} {...input} placeholder={placeholder} />
    {meta.error && meta.touched && (
      <Text style={styles.errorTitle}>{meta.error}</Text>
    )}
  </View>
);

const Button = ({ handleSubmit }) => (
  <TouchableOpacity
    style={[styles.button, styles.container]}
    onPress={handleSubmit}>
    <Text style={styles.buttonTitle}>Giriş</Text>
  </TouchableOpacity>
);

field.js

const CustomField = ({ name, placeholder, label, validate }) => {
  return (
    <Field
      {...{ name, validate }}
      render={({ input, meta }) => (
        <>
          <CustomTextInput {...{ input, meta, label, placeholder }} />
        </>
      )}
    />
  );
};

form.js

<Form
        initialValues={initialValues}
        onSubmit={values => alert(JSON.stringify(values))}
        render={({ handleSubmit }) => {
          return (
            <>
              <CustomField
                name="email"
                validate={required}
                placeholder="Eposta Giriniz"
                label="Eposta"
              />
              <CustomField
                name="password"
                validate={required}
                placeholder="Şifre Giriniz"
                label="Şifre"
              />
              <CustomField
                name="securityQuestion"
                validate={(required, checkQuestionValue)}
                placeholder="İşlemi yapınız"
                label="2 + 1"
              />
              <Button {...{ handleSubmit }} />
            </>
          );
        }}
      />

styles.js

const styles = {
  safeArea: {
    flex: 1,
    justifyContent: 'center',
  },
  container: {
    margin: 12,
  },
  textInput: {
    borderBottomColor: '#787878',
    backgroundColor: '#f4f4f4',
    padding: 16,
    borderRadius: 8,
    color: 'gray',
    fontFamily: 'Avenir-Medium',
  },
  button: {
    justifyContent: 'center',
    alignItems: 'center',
    backgroundColor: '#6610f2',
    padding: 12,
    borderRadius: 8,
  },
  buttonTitle: {
    fontSize: 18,
    color: 'white',
    fontFamily: 'Avenir-Medium',
  },
  errorTitle: {
    fontSize: 13,
    color: 'red',
    fontFamily: 'Avenir-Medium',
    marginTop: 8,
  },
  labelTitle: {
    marginBottom: 8,
    fontSize: 16,
    fontFamily: 'Avenir-Medium',
  },
};

validation.js

const required = value => !value && 'Lütfen boş bırakmayınız';

const checkQuestionValue = value =>
  isNaN(value)
    ? 'Girilen değer numara olmalı'
    : value == 3
    ? undefined
    : 'Sonuç hatalı';