[iOS] Add support for bar button system items (#2133)

* Add converter for UIBarButtonSystemItem

* Add support for UIBarButtonSystemItem-styled buttons

* Add documentation about systemItem

docs/adding-buttons-to-the-navigator.md

     buttonColor: 'blue', // Set color for the button (can also be used in setButtons function to set different button style programatically)
     buttonFontSize: 14, // Set font size for the button (can also be used in setButtons function to set different button style programatically)
     buttonFontWeight: '600' // Set font weight for the button (can also be used in setButtons function to set different button style programatically)
+    systemItem: 'compose', // Optional, iOS only. Set a system bar button item as the icon. Matches UIBarButtonSystemItem naming.
   }],
   leftButtons: [] // buttons for the left side of the nav bar (optional)
 }
 ```
 
+##### iOS System Items
+On iOS, UIKit supplies some common bar button glyphs for developers to use. The following values can be supplied as values to to `systemItem` to use them as an icon for your button.
+
+* `done`
+* `cancel`
+* `edit`
+* `save`
+* `add`
+* `flexibleSpace`
+* `fixedSpace`
+* `compose`
+* `reply`
+* `action`
+* `organize`
+* `bookmarks`
+* `search`
+* `refresh`
+* `stop`
+* `camera`
+* `trash`
+* `play`
+* `pause`
+* `rewind`
+* `fastForward`
+* `undo`
+* `redo`
+
+More information about these glyphs can be found in [Apple's Human Interface Guidelines](https://developer.apple.com/ios/human-interface-guidelines/icons-and-images/system-icons/).
+
+
 ##### Android left button
 On Android, four button types are supported by default without the need to provide an icon. You can use them by specifying one of the following ids in your left button definition:
 

ios/Helpers/RCTConvert+UIBarButtonSystemItem.h

+#import <UIKit/UIKit.h>
+#import <React/RCTConvert.h>
+
+@interface RCTConvert (UIBarButtonSystemItem)
+
++ (UIBarButtonSystemItem)UIBarButtonSystemItem:(id)json;
+
+@end

ios/Helpers/RCTConvert+UIBarButtonSystemItem.m

+#import <UIKit/UIKit.h>
+#import "RCTConvert+UIBarButtonSystemItem.h"
+
+@implementation RCTConvert (UIBarButtonSystemItem)
+
+RCT_ENUM_CONVERTER(UIBarButtonSystemItem, (@{
+    @"done" : @(UIBarButtonSystemItemDone),
+    @"cancel" : @(UIBarButtonSystemItemCancel),
+    @"edit" : @(UIBarButtonSystemItemEdit),
+    @"save" : @(UIBarButtonSystemItemSave),
+    @"add" : @(UIBarButtonSystemItemAdd),
+    @"flexibleSpace" : @(UIBarButtonSystemItemFlexibleSpace),
+    @"fixedSpace" : @(UIBarButtonSystemItemFixedSpace),
+    @"compose" : @(UIBarButtonSystemItemCompose),
+    @"reply" : @(UIBarButtonSystemItemReply),
+    @"action" : @(UIBarButtonSystemItemAction),
+    @"organize" : @(UIBarButtonSystemItemOrganize),
+    @"bookmarks" : @(UIBarButtonSystemItemBookmarks),
+    @"search" : @(UIBarButtonSystemItemSearch),
+    @"refresh" : @(UIBarButtonSystemItemRefresh),
+    @"stop" : @(UIBarButtonSystemItemStop),
+    @"camera" : @(UIBarButtonSystemItemCamera),
+    @"trash" : @(UIBarButtonSystemItemTrash),
+    @"play" : @(UIBarButtonSystemItemPlay),
+    @"pause" : @(UIBarButtonSystemItemPause),
+    @"rewind" : @(UIBarButtonSystemItemRewind),
+    @"fastForward" : @(UIBarButtonSystemItemFastForward),
+    @"undo" : @(UIBarButtonSystemItemUndo),
+    @"redo" : @(UIBarButtonSystemItemRedo),
+}), UIBarButtonSystemItemDone, integerValue)
+
+@end

ios/RCCNavigationController.m

 #import "RCCCustomBarButtonItem.h"
 #import "UIViewController+Rotation.h"
 #import "RCTHelpers.h"
+#import "RCTConvert+UIBarButtonSystemItem.h"
 
 @implementation RCCNavigationController
 {
     id icon = button[@"icon"];
     if (icon) iconImage = [RCTConvert UIImage:icon];
     NSString *__nullable component = button[@"component"];
+    NSString *__nullable systemItemName = button[@"systemItem"];
+    UIBarButtonSystemItem systemItem = [RCTConvert UIBarButtonSystemItem:systemItemName];
 
     UIBarButtonItem *barButtonItem;
     if (iconImage)
       RCTBridge *bridge = [[RCCManager sharedInstance] getBridge];
       barButtonItem = [[RCCCustomBarButtonItem alloc] initWithComponentName:component passProps:button[@"passProps"] bridge:bridge];
     }
+    else if (systemItemName) {
+      barButtonItem = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:systemItem target:self action:@selector(onButtonPress:)];
+    }
     else continue;
     objc_setAssociatedObject(barButtonItem, &CALLBACK_ASSOCIATED_KEY, button[@"onPress"], OBJC_ASSOCIATION_RETAIN_NONATOMIC);
     [barButtonItems addObject:barButtonItem];

ios/ReactNativeNavigation.xcodeproj/project.pbxproj

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+		2DDE72091FB27E730017290C /* RCTConvert+UIBarButtonSystemItem.m in Sources */ = {isa = PBXBuildFile; fileRef = 2DDE72071FB27E720017290C /* RCTConvert+UIBarButtonSystemItem.m */; };
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 		2DCD49981F33AAC30035123A /* RCCCustomBarButtonItem.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = RCCCustomBarButtonItem.m; sourceTree = "<group>"; };
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+		2DDE72071FB27E720017290C /* RCTConvert+UIBarButtonSystemItem.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = "RCTConvert+UIBarButtonSystemItem.m"; sourceTree = "<group>"; };
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 		D8D779951D04B7180050CFEA /* Helpers */ = {
 			isa = PBXGroup;
 			children = (
+				2DDE72081FB27E730017290C /* RCTConvert+UIBarButtonSystemItem.h */,
+				2DDE72071FB27E720017290C /* RCTConvert+UIBarButtonSystemItem.m */,
 				2611087E1E6C495400BF5D98 /* UIViewController+Rotation.h */,
 				2611087F1E6C495400BF5D98 /* UIViewController+Rotation.m */,
 				D8D779961D04B7180050CFEA /* RCTHelpers.h */,
 				D85082E41CBCF54200FDB961 /* SidebarAnimation.m in Sources */,
 				D8E11C571CBD1F670018B644 /* RCCDrawerController.m in Sources */,
 				260804DB1CE0D9D20094DBA1 /* RCCToolBar.m in Sources */,
+				2DDE72091FB27E730017290C /* RCTConvert+UIBarButtonSystemItem.m in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};