- Adding locale prop to DatePickerIOS

Summary:
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While building a React Native application, I've come across the use case of wanting to set a specific locale for DatePickers irrespective of the users OS region setting. Since this is a feature available to native DatePicker components, I think it would be helpful to expose this in React Native as well.

Testing can be done by passing a `locale` prop to a DatePickerIOS. Example:

```
<DatePickerIOS
  date={this.state.date}
  mode="date"
  locale="fr_FR"
  onDateChange={date => this.setState({ date: date })}
/>
```

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  CATEGORY
[----------]        TYPE
[ CLI      ]   [-------------]      LOCATION
[ DOCS     ]   [ BREAKING    ]   [-------------]
[ GENERAl  ]   [ BUGFIX      ]   [-{Component}-]
[ INTERNAL ]   [ ENHANCEMENT ]   [ {File}      ]
[ IOS      ]   [ FEATURE     ]   [ {Directory} ]   |-----------|
[ ANDROID  ]   [ MINOR       ]   [ {Framework} ] - | {Message} |
[----------]   [-------------]   [-------------]   |-----------|

[CATEGORY] [TYPE] [LOCATION] - MESSAGE

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 [IOS] [BREAKING] [FlatList] - Change a thing that breaks other things
 [ANDROID] [BUGFIX] [TextInput] - Did a thing to TextInput
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[IOS][ENHANCEMENT][DatePickerIOS] - Adding a locale prop.
Closes #16639

Differential Revision: D6241981

Pulled By: hramos

fbshipit-source-id: 77b1b85c09f3e12d6b3e103b3d1ffd1f12e2cea9

Libraries/Components/DatePicker/DatePickerIOS.ios.js

@@ -78,6 +78,11 @@ const DatePickerIOS = createReactClass({
      */
     mode: PropTypes.oneOf(['date', 'time', 'datetime']),
 
+    /**
+     * The date picker locale.
+     */
+    locale: PropTypes.string,
+
     /**
      * The interval at which minutes can be selected.
      */
@@ -127,6 +132,7 @@ const DatePickerIOS = createReactClass({
           ref={ picker => { this._picker = picker; } }
           style={styles.datePickerIOS}
           date={props.date.getTime()}
+          locale={props.locale ? props.locale : undefined}
           maximumDate={
             props.maximumDate ? props.maximumDate.getTime() : undefined
           }
@@ -155,6 +161,7 @@ const RCTDatePickerIOS = requireNativeComponent('RCTDatePicker', {
   propTypes: {
     ...DatePickerIOS.propTypes,
     date: PropTypes.number,
+    locale: PropTypes.string,
     minimumDate: PropTypes.number,
     maximumDate: PropTypes.number,
     onDateChange: () => null,

React/Base/RCTConvert.h

@@ -55,6 +55,7 @@ typedef NSURL RCTFileURL;
 + (RCTFileURL *)RCTFileURL:(id)json;
 
 + (NSDate *)NSDate:(id)json;
++ (NSLocale *)NSLocale:(id)json;
 + (NSTimeZone *)NSTimeZone:(id)json;
 + (NSTimeInterval)NSTimeInterval:(id)json;
 

React/Base/RCTConvert.m

@@ -222,6 +222,20 @@ + (NSDate *)NSDate:(id)json
   return nil;
 }
 
++ (NSLocale *)NSLocale:(id)json
+{
+  if ([json isKindOfClass:[NSString class]]) {
+    NSLocale *locale = [[NSLocale alloc] initWithLocaleIdentifier:json];
+    if (!locale) {
+      RCTLogError(@"JSON String '%@' could not be interpreted as a valid locale. ", json);
+    }
+    return locale;
+  } else if (json) {
+    RCTLogConvertError(json, @"a locale");
+  }
+  return nil;
+}
+
 // JS Standard for time is milliseconds
 RCT_CUSTOM_CONVERTER(NSTimeInterval, NSTimeInterval, [self double:json] / 1000.0)
 

React/Views/RCTDatePickerManager.m

@@ -35,6 +35,7 @@ - (UIView *)view
 }
 
 RCT_EXPORT_VIEW_PROPERTY(date, NSDate)
+RCT_EXPORT_VIEW_PROPERTY(locale, NSLocale)
 RCT_EXPORT_VIEW_PROPERTY(minimumDate, NSDate)
 RCT_EXPORT_VIEW_PROPERTY(maximumDate, NSDate)
 RCT_EXPORT_VIEW_PROPERTY(minuteInterval, NSInteger)