Flutter - 编写iOS特定代码

访问iOS特定代码与Android平台类似，只是它使用iOS特定的语言 - Objective-C或Swift和iOS SDK。否则，概念与Android平台相同。

让我们为iOS平台编写与上一章相同的应用程序。

• 让我们在Android Studio（macOS）中创建一个新的应用程序，flutter_browser_ios_app

• 按照上一章中的步骤2-6操作。

• 启动XCode并点击文件→打开

• 选择Flutter项目ios目录下的xcode项目。

• 打开Runner → Runner路径下的AppDelegate.m。它包含以下代码：

#include "AppDelegate.h" 
#include "GeneratedPluginRegistrant.h" 
@implementation AppDelegate 

- (BOOL)application:(UIApplication *)application
   didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
      // [GeneratedPluginRegistrant registerWithRegistry:self];
      // Override point for customization after application launch.
      return [super application:application didFinishLaunchingWithOptions:launchOptions];
   } 
@end

• 我们添加了一个方法openBrowser，用于使用指定的url打开浏览器。它接受单个参数url。

- (void)openBrowser:(NSString *)urlString { 
   NSURL *url = [NSURL URLWithString:urlString]; 
   UIApplication *application = [UIApplication sharedApplication]; 
   [application openURL:url]; 
}

• 在didFinishLaunchingWithOptions方法中，找到控制器并在controller变量中设置它。

FlutterViewController* controller = (FlutterViewController*)self.window.rootViewController;

• 在didFinishLaunchingWithOptions方法中，将浏览器通道设置为flutterapp.tutorialspoint.com/browse：

FlutterMethodChannel* browserChannel = [
   FlutterMethodChannel methodChannelWithName:
   @"flutterapp.tutorialspoint.com/browser" binaryMessenger:controller];

• 创建一个变量weakSelf并设置当前类：

__weak typeof(self) weakSelf = self;

• 现在，实现setMethodCallHandler。通过匹配call.method调用openBrowser。通过调用call.arguments获取url，并在调用openBrowser时传递它。

[browserChannel setMethodCallHandler:^(FlutterMethodCall* call, FlutterResult result) {
   if ([@"openBrowser" isEqualToString:call.method]) { 
      NSString *url = call.arguments[@"url"];   
      [weakSelf openBrowser:url]; 
   } else { result(FlutterMethodNotImplemented); } 
}];

• 完整的代码如下：

#include "AppDelegate.h" 
#include "GeneratedPluginRegistrant.h" 
@implementation AppDelegate 

- (BOOL)application:(UIApplication *)application 
   didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
   
   // custom code starts 
   FlutterViewController* controller = (FlutterViewController*)self.window.rootViewController; 
   FlutterMethodChannel* browserChannel = [
      FlutterMethodChannel methodChannelWithName:
      @"flutterapp.tutorialspoint.com /browser" binaryMessenger:controller]; 
   
   __weak typeof(self) weakSelf = self; 
   [browserChannel setMethodCallHandler:^(
      FlutterMethodCall* call, FlutterResult result) { 
      
      if ([@"openBrowser" isEqualToString:call.method]) { 
         NSString *url = call.arguments[@"url"];
         [weakSelf openBrowser:url]; 
      } else { result(FlutterMethodNotImplemented); } 
   }]; 
   // custom code ends 
   [GeneratedPluginRegistrant registerWithRegistry:self]; 
   
   // Override point for customization after application launch. 
   return [super application:application didFinishLaunchingWithOptions:launchOptions]; 
}
- (void)openBrowser:(NSString *)urlString { 
   NSURL *url = [NSURL URLWithString:urlString]; 
   UIApplication *application = [UIApplication sharedApplication]; 
   [application openURL:url]; 
} 
@end

• 打开项目设置。

• 转到功能并启用后台模式。

• 添加*后台获取和远程通知**。

• 现在，运行应用程序。它的工作方式类似于Android版本，但将打开Safari浏览器而不是Chrome浏览器。