Flutter编写IOS代码

访问iOS特定代码与Android平台上的代码相似，不同之处在于它使用iOS特定语言-Objective-C或Swift和iOS SDK。

下表显示了如何在Android和iOS平台上接收Dart值。

dart	android	ios
null	null	无(嵌套时为NSNull)
bool	java.lang.Boolean	NSNumber numberWithBool:
int	java.lang.Integer	NSNumber numberWithInt:
double	java.lang.Double	NSNumber numberWithDouble:
String	java.lang.String	NSString:
Uint8List	byte[]	FlutterStandardTypedData typedDataWithBytes:
Int32List	int[]	FlutterStandardTypedData typedDataWithInt32:
Int64List	long[]	FlutterStandardTypedData typedDataWithInt64:
Float64List	double[]	FlutterStandardTypedData typedDataWithFloat64:
List	java.util.ArrayList	NSArray
Map	java.util.HashMap	NSDictionary

让无涯教程也为iOS平台编写与上一章相同的应用程序。

• 让无涯教程在Android Studio(macOS)中创建一个新应用， flutter_browser_ios_app

• 启动XCode并单击 File→Open

• 在flutter项目的ios目录下选择xcode项目。

• 在 Runner→Runner path 下打开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

• 无涯教程添加了openBrowser方法来打开具有指定URL的浏览器。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，找到控制器并将其设置在控制器变量中。

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

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

FlutterMethodChannel* browserChannel = [
   FlutterMethodChannel methodChannelWithName:
   @"flutterapp.learnfk.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.learnfk.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); } 
   }]; 
   //自定义代码结束
   [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

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。