feat(keychain): add Keychain plugin (#1420)

* feat(keychain): adding keychain plugin

ionic-native for cordova ios keychain plugin

* feat(keychain): make touchID params optional in type def

src/@ionic-native/plugins/keychain/index.ts

@@ -0,0 +1,94 @@
+import { Injectable } from '@angular/core';
+import { Cordova, Plugin } from '@ionic-native/core';
+
+
+/**
+ * @name Keychain
+ * @description
+ * Get and set data in the iOS Keychain
+ *
+ * Requires Cordova plugin: `cordova-plugin-ios-keychain`. For more info, please see the [Keychain plugin docs](https://github.com/driftyco/cordova-plugin-ios-keychain).
+ *
+ * @usage
+ * ```typescript
+ * import { Keychain } from '@ionic-native/keychain';
+ *
+ * constructor(private keychain: Keychain) { }
+ *
+ * ...
+ *
+ * this.keychain.set(key, value).then(() => {
+ *   this.keychain.get(key)
+ *     .then(value => console.log('Got value', value))
+ *     .catch(err => console.error('Error getting', err));
+ * })
+ * .catch(err => console.error('Error setting', err));
+ * ```
+ */
+@Plugin({
+  pluginName: 'Keychain',
+  plugin: 'cordova-plugin-ios-keychain',
+  pluginRef: 'window.Keychain',
+  repo: 'https://github.com/driftyco/cordova-plugin-ios-keychain/',
+  platforms: ['iOS']
+})
+@Injectable()
+export class Keychain {
+
+  /**
+   * Retrieves a value for a key
+   *
+   * @param {string} key the key to retrieve
+   * @param {string} TouchIDMessage the message to show underneath the TouchID prompt (if any)
+   */
+  @Cordova({
+    callbackOrder: 'reverse'
+  })
+  get(key: string, touchIDMessage?: string): Promise<any> { return; }
+
+  /**
+   * Sets a value for a key
+   *
+   * @param {string} key the key to set
+   * @param {string|number|boolean} value the value to set
+   * @param {boolean} useTouchID whether to store the value with security such that TouchID will be needed to grab it
+   */
+  @Cordova({
+    callbackOrder: 'reverse'
+  })
+  set(key: string, value: string|number|boolean, useTouchID?: boolean): Promise<any> { return; }
+
+  /**
+   * Gets a JSON value for a key
+   *
+   * @param {string} key the key to retrieve
+   * @param {string} TouchIDMessage the message to show underneath the TouchID prompt (if any)
+   */
+  @Cordova({
+    callbackOrder: 'reverse'
+  })
+  getJson(key: string, touchIDMessage?: string): Promise<any> { return; }
+
+  /**
+   * Sets a JSON value for a key
+   *
+   * @param {string} key the key to set
+   * @param {any} value the value to set
+   * @param {boolean} Wether to store the value with security such that TouchID will be needed to grab it
+   */
+  @Cordova({
+    callbackOrder: 'reverse'
+  })
+  setJson(key: string, obj: any, useTouchId?: boolean): Promise<any> { return; }
+
+  /**
+   * Removes a value for a key
+   *
+   * @param {string} key the key to remove
+   */
+  @Cordova({
+    callbackOrder: 'reverse'
+  })
+  remove(key: string): Promise<any> { return; }
+
+}