iOS项目开发：集成flutter模块找不到自定义插件

写了一个插件，在纯flutter环境下可以正常运行，可是在将flutter项目集成到iOS项目中，用Xcode启动iOS项目，进入flutter界面，却报以下错误：文章源自菜鸟学院-https://www.cainiaoxueyuan.com/xcx/10470.html

Unhandled Exception: MissingPluginException(No implementation found for method getPlatformVersion on channel koolearn_test)

代码如下：文章源自菜鸟学院-https://www.cainiaoxueyuan.com/xcx/10470.html

AppDelegate:文章源自菜鸟学院-https://www.cainiaoxueyuan.com/xcx/10470.html

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    
    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
    self.window.rootViewController = [[ViewController alloc] init];
    self.window.backgroundColor = [UIColor whiteColor];
    [self.window makeKeyAndVisible];
    
    return [super application:application didFinishLaunchingWithOptions:launchOptions];
}

ViewController:文章源自菜鸟学院-https://www.cainiaoxueyuan.com/xcx/10470.html

#import ""
#import <Flutter/Flutter.h>

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
}

- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
    FlutterViewController* flutterViewController = [[FlutterViewController alloc] init];
    [self presentViewController:flutterViewController animated:false completion:nil];
}

第一次尝试：引入GeneratedPluginRegistrant

在创建插件工程的时候，flutter插件目录下会自动生成一个example文件，里面是插件的测试工程。打开iOS测试工程，在AppDelegate类中，发现比我写的插件代码多了一行注册代码，果断加入iOS项目。文章源自菜鸟学院-https://www.cainiaoxueyuan.com/xcx/10470.html

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
   
    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
    self.window.rootViewController = [[ViewController alloc] init];
    self.window.backgroundColor = [UIColor whiteColor];
    [self.window makeKeyAndVisible];

    [GeneratedPluginRegistrant registerWithRegistry:self];

    return [super application:application didFinishLaunchingWithOptions:launchOptions];
}

尝试结果：失败，仍旧报上面错误文章源自菜鸟学院-https://www.cainiaoxueyuan.com/xcx/10470.html

第二次尝试：将RootViewController设置为FlutterViewController

在咸鱼的博客上看到一个解决方法，就是把RootViewController设置为FlutterViewController。测试OK，错误解决。但是我们的工程首页是Native页面，所以Window的rootViewController不能是FlutterViewController。文章源自菜鸟学院-https://www.cainiaoxueyuan.com/xcx/10470.html

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    
    // 显示Window
    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
    [self.window setRootViewController:[[FlutterViewController alloc] initWithNibName:nil bundle:nil]];
    [self.window setBackgroundColor:[UIColor whiteColor]];
    [self.window makeKeyAndVisible];

    [GeneratedPluginRegistrant registerWithRegistry:self];
    
    return [super application:application didFinishLaunchingWithOptions:launchOptions];
}

第三次尝试：引入FlutterEngine

最后在flutter的wiki上发现了一种新的解决办法，新建一个FlutterEngine，让FlutterEngine作为插件的注册对象，问题解决。文章源自菜鸟学院-https://www.cainiaoxueyuan.com/xcx/10470.html

AppDelegate:文章源自菜鸟学院-https://www.cainiaoxueyuan.com/xcx/10470.html

#import <UIKit/UIKit.h>
#import <Flutter/Flutter.h>

@interface AppDelegate : FlutterAppDelegate

@property (nonatomic,strong) FlutterEngine *flutterEngine;

@end

@implementation AppDelegate

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    
    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
    self.window.rootViewController = [[ViewController alloc] init];
    self.window.backgroundColor = [UIColor whiteColor];
    [self.window makeKeyAndVisible];
    
     = [[FlutterEngine alloc] initWithName:@"" project:nil];
    [ runWithEntrypoint:nil];
    [GeneratedPluginRegistrant registerWithRegistry:];

    return [super application:application didFinishLaunchingWithOptions:launchOptions];
}

@end

ViewController:文章源自菜鸟学院-https://www.cainiaoxueyuan.com/xcx/10470.html

#import ""
#import <Flutter/Flutter.h>
#import ""

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
}

- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
    FlutterEngine *flutterEngine = [(AppDelegate *)[[UIApplication sharedApplication] delegate] flutterEngine];
    FlutterViewController *flutterViewController = [[FlutterViewController alloc] initWithEngine:flutterEngine nibName:nil bundle:nil];
    [self presentViewController:flutterViewController animated:false completion:nil];
}

@end

碰到错误

运行Xcode工程，如果报以下错误，那么对工程进行pod install 或 pod update文章源自菜鸟学院-https://www.cainiaoxueyuan.com/xcx/10470.html