Implement WKWebView to replace WebView

Summary:
@public

`UIWebView` has been deprecated and replaced by `WKWebView`. This diff introduces a new component `WKWebView` that simply renders a `WKWebView` on iOS.

This is the first in the stack of many diffs that'll be required to fully replace `UIWebView` with `WKWebView` in the `<WebView/>` React Native component. Eventually, I hope to introduce a prop called `useWebKitImplementation`, which, when true, will force RN to use `WKWebView` instead of `UIWebView` for the `<WebView/>` component.

The only thing that's been implemented so far is the `source` property.

Reviewed By: mmmulani

Differential Revision: D6266100

fbshipit-source-id: 65862e34bd98db7fff0349cf26888afee43a56e4

Author: RSNara

Libraries/Components/WKWebView/WKWebView.android.js

@@ -0,0 +1,22 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @format
+ * @flow
+ * @providesModule WKWebView
+ */
+
+const React = require('React');
+const View = require('View');
+const Text = require('Text');
+
+module.exports = () => {
+  return (
+    <View>
+      <Text>Android version not implemented.</Text>
+    </View>
+  );
+};

Libraries/Components/WKWebView/WKWebView.ios.js

@@ -0,0 +1,14 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @format
+ * @flow
+ * @providesModule WKWebView
+ */
+
+const requireNativeComponent = require('requireNativeComponent');
+
+module.exports = requireNativeComponent('RCTWKWebView');

React/Views/RCTWKWebView.h

@@ -0,0 +1,22 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#import <React/RCTView.h>
+
+@class RCTWKWebView;
+
+@protocol RCTWKWebViewDelegate <NSObject>
+@end
+
+@interface RCTWKWebView : RCTView
+
+@property (nonatomic, weak) id<RCTWKWebViewDelegate> delegate;
+@property (nonatomic, copy) NSDictionary *source;
+
+@end

React/Views/RCTWKWebView.m

@@ -0,0 +1,72 @@
+#import "RCTWKWebView.h"
+
+#import <WebKit/WebKit.h>
+
+#import <React/RCTConvert.h>
+
+#import "RCTAutoInsetsProtocol.h"
+
+@interface RCTWKWebView () <WKUIDelegate>
+@end
+
+@implementation RCTWKWebView
+{
+  WKWebView *_webView;
+}
+
+- (void)dealloc
+{
+
+}
+
+- (instancetype)initWithFrame:(CGRect)frame
+{
+  if ((self = [super initWithFrame:frame])) {
+    super.backgroundColor = [UIColor clearColor];
+    _webView = [[WKWebView alloc] initWithFrame:self.bounds];
+    _webView.UIDelegate = self;
+    [self addSubview:_webView];
+  }
+  return self;
+}
+
+- (void)setSource:(NSDictionary *)source
+{
+  if (![_source isEqualToDictionary:source]) {
+    _source = [source copy];
+
+    // Check for a static html source first
+    NSString *html = [RCTConvert NSString:source[@"html"]];
+    if (html) {
+      NSURL *baseURL = [RCTConvert NSURL:source[@"baseUrl"]];
+      if (!baseURL) {
+        baseURL = [NSURL URLWithString:@"about:blank"];
+      }
+      [_webView loadHTMLString:html baseURL:baseURL];
+      return;
+    }
+
+    NSURLRequest *request = [RCTConvert NSURLRequest:source];
+    // Because of the way React works, as pages redirect, we actually end up
+    // passing the redirect urls back here, so we ignore them if trying to load
+    // the same url. We'll expose a call to 'reload' to allow a user to load
+    // the existing page.
+    if ([request.URL isEqual:_webView.URL]) {
+      return;
+    }
+    if (!request.URL) {
+      // Clear the webview
+      [_webView loadHTMLString:@"" baseURL:nil];
+      return;
+    }
+    [_webView loadRequest:request];
+  }
+}
+
+- (void)layoutSubviews
+{
+  [super layoutSubviews];
+  _webView.frame = self.bounds;
+}
+
+@end

React/Views/RCTWKWebViewManager.m

@@ -0,0 +1,18 @@
+#import "RCTViewManager.h"
+#import "RCTWKWebView.h"
+
+@interface RCTWKWebViewManager : RCTViewManager
+@end
+
+@implementation RCTWKWebViewManager
+
+RCT_EXPORT_MODULE()
+
+- (UIView *)view
+{
+  return [RCTWKWebView new];
+}
+
+RCT_EXPORT_VIEW_PROPERTY(source, NSDictionary)
+
+@end