PickerModal - support onShow (#1340)

* PickerModal - support onShow

* Revert unrelated changes

Author: M-i-k-e-l

src/components/picker/PickerModal.js

@@ -78,14 +78,15 @@ class PickerModal extends BaseComponent {
   };
 
   render() {
-    const {visible, enableModalBlur, topBarProps, listProps, children} = this.props;
+    const {visible, enableModalBlur, topBarProps, listProps, children, onShow} = this.props;
     return (
       <Modal
         animationType={'slide'}
         transparent={Constants.isIOS && enableModalBlur}
         enableModalBlur={Constants.isIOS && enableModalBlur}
         visible={visible}
         onRequestClose={topBarProps.onCancel}
+        onShow={onShow}
       >
         <Modal.TopBar {...topBarProps}/>
         {this.renderSearchInput()}

src/components/picker/index.js

@@ -350,6 +350,7 @@ class Picker extends Component {
       enableModalBlur,
       topBarProps,
       showSearch,
+      onShow,
       searchStyle,
       searchPlaceholder,
       renderCustomSearch,
@@ -397,6 +398,7 @@ class Picker extends Component {
           onSearchChange={this.onSearchChange}
           renderCustomSearch={renderCustomSearch}
           listProps={listProps}
+          onShow={onShow}
         >
           {this.children} 
         </PickerModal>