Open Source FirebaseDynamicLinks (#1842)

Firebase/DynamicLinks/FIRDLJavaScriptExecutor.m

@@ -0,0 +1,182 @@
+/*
+ * Copyright 2018 Google
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#import <WebKit/WebKit.h>
+
+#import "DynamicLinks/FIRDLJavaScriptExecutor.h"
+
+// define below needed because nullability of UIWebViewDelegate method param was changed between
+// iOS SDK versions
+#if (defined(__IPHONE_10_0) && (__IPHONE_OS_VERSION_MAX_ALLOWED >= __IPHONE_10_0))
+#define FIRDL_NULLABLE_IOS9_NONNULLABLE_IOS10 nonnull
+#else
+#define FIRDL_NULLABLE_IOS9_NONNULLABLE_IOS10 nullable
+#endif
+
+NS_ASSUME_NONNULL_BEGIN
+
+static NSString *const kJSMethodName = @"generateFingerprint";
+
+/** Creates and returns the FDL JS method name. */
+NSString *FIRDLTypeofFingerprintJSMethodNameString() {
+  static NSString *methodName;
+  static dispatch_once_t onceToken;
+  dispatch_once(&onceToken, ^{
+    methodName = [NSString stringWithFormat:@"typeof(%@)", kJSMethodName];
+  });
+  return methodName;
+}
+
+/** Creates and returns the FDL JS method definition. */
+NSString *GINFingerprintJSMethodString() {
+  static NSString *methodString;
+  static dispatch_once_t onceToken;
+  dispatch_once(&onceToken, ^{
+    methodString = [NSString stringWithFormat:@"%@()", kJSMethodName];
+  });
+  return methodString;
+}
+
+@interface FIRDLJavaScriptExecutor () <UIWebViewDelegate, WKNavigationDelegate>
+@end
+
+@implementation FIRDLJavaScriptExecutor {
+  __weak id<FIRDLJavaScriptExecutorDelegate> _delegate;
+  NSString *_script;
+
+  // Web views with which to run JavaScript.
+  UIWebView *_uiWebView;  // Used in iOS 7 only.
+  WKWebView *_wkWebView;  // Used in iOS 8+ only.
+}
+
+- (instancetype)initWithDelegate:(id<FIRDLJavaScriptExecutorDelegate>)delegate
+                          script:(NSString *)script {
+  NSParameterAssert(delegate);
+  NSParameterAssert(script);
+  NSParameterAssert(script.length > 0);
+  NSAssert([NSThread isMainThread], @"%@ must be used in main thread",
+           NSStringFromClass([self class]));
+  if (self = [super init]) {
+    _delegate = delegate;
+    _script = [script copy];
+    [self start];
+  }
+  return self;
+}
+
+#pragma mark - Internal methods
+- (void)start {
+  NSString *htmlContent =
+      [NSString stringWithFormat:@"<html><head><script>%@</script></head></html>", _script];
+
+  // Use WKWebView if available as it executes JavaScript more quickly, otherwise, fall back
+  // on UIWebView.
+  if ([WKWebView class]) {
+    _wkWebView = [[WKWebView alloc] init];
+    _wkWebView.navigationDelegate = self;
+    [_wkWebView loadHTMLString:htmlContent baseURL:nil];
+  } else {
+    _uiWebView = [[UIWebView alloc] init];
+    _uiWebView.delegate = self;
+    [_uiWebView loadHTMLString:htmlContent baseURL:nil];
+  }
+}
+
+- (void)handleExecutionResult:(NSString *)result {
+  [self cleanup];
+  [_delegate javaScriptExecutor:self completedExecutionWithResult:result];
+}
+
+- (void)handleExecutionError:(nullable NSError *)error {
+  [self cleanup];
+  if (!error) {
+    error = [NSError errorWithDomain:@"com.firebase.durabledeeplink" code:-1 userInfo:nil];
+  }
+  [_delegate javaScriptExecutor:self failedWithError:error];
+}
+
+- (void)cleanup {
+  _uiWebView.delegate = nil;
+  _uiWebView = nil;
+  _wkWebView.navigationDelegate = nil;
+  _wkWebView = nil;
+}
+
+#pragma mark - WKNavigationDelegate
+
+- (void)webView:(WKWebView *)webView
+    didFinishNavigation:(null_unspecified WKNavigation *)navigation {
+  __weak __typeof__(self) weakSelf = self;
+
+  // Make sure that the javascript was loaded successfully before calling the method.
+  [webView evaluateJavaScript:FIRDLTypeofFingerprintJSMethodNameString()
+            completionHandler:^(id _Nullable typeofResult, NSError *_Nullable typeError) {
+              if (typeError) {
+                [weakSelf handleExecutionError:typeError];
+                return;
+              }
+              if ([typeofResult isEqual:@"function"]) {
+                [webView
+                    evaluateJavaScript:GINFingerprintJSMethodString()
+                     completionHandler:^(id _Nullable result, NSError *_Nullable functionError) {
+                       if ([result isKindOfClass:[NSString class]]) {
+                         [weakSelf handleExecutionResult:result];
+                       } else {
+                         [weakSelf handleExecutionError:nil];
+                       }
+                     }];
+              } else {
+                [weakSelf handleExecutionError:nil];
+              }
+            }];
+}
+
+- (void)webView:(WKWebView *)webView
+    didFailNavigation:(null_unspecified WKNavigation *)navigation
+            withError:(NSError *)error {
+  [self handleExecutionError:error];
+}
+
+#pragma mark - UIWebViewDelegate
+
+- (void)webViewDidFinishLoad:(UIWebView *)webView {
+  // Make sure that the javascript was loaded successfully before calling the method.
+  NSString *methodType =
+      [webView stringByEvaluatingJavaScriptFromString:FIRDLTypeofFingerprintJSMethodNameString()];
+  if (![methodType isEqualToString:@"function"]) {
+    // Javascript was not loaded successfully.
+    [self handleExecutionError:nil];
+    return;
+  }
+
+  // Get the result from javascript.
+  NSString *result =
+      [webView stringByEvaluatingJavaScriptFromString:GINFingerprintJSMethodString()];
+  if ([result isKindOfClass:[NSString class]]) {
+    [self handleExecutionResult:result];
+  } else {
+    [self handleExecutionError:nil];
+  }
+}
+
+- (void)webView:(UIWebView *)webView
+    didFailLoadWithError:(FIRDL_NULLABLE_IOS9_NONNULLABLE_IOS10 NSError *)error {
+  [self handleExecutionError:error];
+}
+
+@end
+
+NS_ASSUME_NONNULL_END