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- (void)viewDidLoad {
[super viewDidLoad];
// Make a button to call the showFlutter function when pressed.
UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
[button addTarget:self
action:@selector(showFlutter)
forControlEvents:UIControlEventTouchUpInside];
[button setTitle:@"Show Flutter!" forState:UIControlStateNormal];
button.backgroundColor = UIColor.blueColor;
button.frame = CGRectMake(80.0, 210.0, 160.0, 40.0);
[self.view addSubview:button];
}
- (void)showFlutter {
FlutterEngine *flutterEngine =
((AppDelegate *)UIApplication.sharedApplication.delegate).flutterEngine;
FlutterViewController *flutterViewController =
[[FlutterViewController alloc] initWithEngine:flutterEngine nibName:nil bundle:nil];
[self presentViewController:flutterViewController animated:YES completion:nil];
}
@end<code_end>
Now, you have a Flutter screen embedded in your iOS app.info Note
Using the previous example, the default main()
entrypoint function of your default Dart library
would run when calling run on the
FlutterEngine created in the AppDelegate.<topic_end>
<topic_start>
Alternatively - Create a FlutterViewController with an implicit FlutterEngine
As an alternative to the previous example, you can let the
FlutterViewController implicitly create its own FlutterEngine without
pre-warming one ahead of time.This is not usually recommended because creating a
FlutterEngine on-demand could introduce a noticeable
latency between when the FlutterViewController is
presented and when it renders its first frame. This could, however, be
useful if the Flutter screen is rarely shown, when there are no good
heuristics to determine when the Dart VM should be started, and when Flutter
doesn’t need to persist state between view controllers.To let the FlutterViewController present without an existing
FlutterEngine, omit the FlutterEngine construction, and create the
FlutterViewController without an engine reference.
<code_start>// Existing code omitted.
func showFlutter() {
let flutterViewController = FlutterViewController(project: nil, nibName: nil, bundle: nil)
present(flutterViewController, animated: true, completion: nil)
}<code_end>
<code_start>// Existing code omitted.
- (void)showFlutter {
FlutterViewController *flutterViewController =
[[FlutterViewController alloc] initWithProject:nil nibName:nil bundle:nil];
[self presentViewController:flutterViewController animated:YES completion:nil];
}
@end<code_end>
See Loading sequence and performance
for more explorations on latency and memory usage.<topic_end>
<topic_start>
Using the FlutterAppDelegate
Letting your application’s UIApplicationDelegate subclass
FlutterAppDelegate is recommended but not required.The FlutterAppDelegate performs functions such as:<topic_end>
<topic_start>
Creating a FlutterAppDelegate subclass
Creating a subclass of the FlutterAppDelegate in UIKit apps was shown
in the Start a FlutterEngine and FlutterViewController section.
In a SwiftUI app, you can create a subclass of the
FlutterAppDelegate that conforms to the ObservableObject protocol as follows:Then, in your view, the AppDelegateis accessible as an EnvironmentObject.<topic_end>
<topic_start>
If you can’t directly make FlutterAppDelegate a subclass
If your app delegate can’t directly make FlutterAppDelegate a subclass,
make your app delegate implement the FlutterAppLifeCycleProvider
protocol in order to make sure your plugins receive the necessary callbacks.
Otherwise, plugins that depend on these events might have undefined behavior.For instance:
<code_start>import Foundation
import Flutter
class AppDelegate: UIResponder, UIApplicationDelegate, FlutterAppLifeCycleProvider, ObservableObject {
private let lifecycleDelegate = FlutterPluginAppLifeCycleDelegate()
let flutterEngine = FlutterEngine(name: "flutter_nps_engine")
override func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey : Any]? = nil) -> Bool {
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey : Any]? = nil) -> Bool {
flutterEngine.run()
return lifecycleDelegate.application(application, didFinishLaunchingWithOptions: launchOptions ?? [:])
}
func application(_ application: UIApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: Data) {
lifecycleDelegate.application(application, didRegisterForRemoteNotificationsWithDeviceToken: deviceToken)
}
func application(_ application: UIApplication, didFailToRegisterForRemoteNotificationsWithError error: Error) {
lifecycleDelegate.application(application, didFailToRegisterForRemoteNotificationsWithError: error)
}
func application(_ application: UIApplication, didReceiveRemoteNotification userInfo: [AnyHashable : Any], fetchCompletionHandler completionHandler: @escaping (UIBackgroundFetchResult) -> Void) {
lifecycleDelegate.application(application, didReceiveRemoteNotification: userInfo, fetchCompletionHandler: completionHandler)
}
func application(_ app: UIApplication, open url: URL, options: [UIApplication.OpenURLOptionsKey : Any] = [:]) -> Bool {
return lifecycleDelegate.application(app, open: url, options: options)
}
func application(_ application: UIApplication, handleOpen url: URL) -> Bool {
return lifecycleDelegate.application(application, handleOpen: url)
}
func application(_ application: UIApplication, open url: URL, sourceApplication: String?, annotation: Any) -> Bool {
return lifecycleDelegate.application(application, open: url, sourceApplication: sourceApplication ?? "", annotation: annotation)
}
func application(_ application: UIApplication, performActionFor shortcutItem: UIApplicationShortcutItem, completionHandler: @escaping (Bool) -> Void) {
lifecycleDelegate.application(application, performActionFor: shortcutItem, completionHandler: completionHandler)
}
func application(_ application: UIApplication, handleEventsForBackgroundURLSession identifier: String, completionHandler: @escaping () -> Void) {