我正在使用Flutter开发一个应用程序。但我陷入一种困境，即Android设备具有默认的后退按钮，而iPhone没有。因此，当我在iOS设备中打开应用程序时，需要显示后退按钮。 另外，如果还有其他内置功能可用，请指导我。
答案 0 :(得分：0)
默认情况下，我们将为Android和iOS的两者 获取backButton 。如果我们不想要它，可以通过将空容器（Container()）赋予appBar的leading值来删除。有关更多详细信息，请参见this
答案 1 :(得分：0)
将tsconfig.json与func setCurrentLocation(location: CLLocation) {
let encodedLocation = NSKeyedArchiver.archivedData(withRootObject: location)
UserDefaults.standard.set(encodedLocation, forKey: UserDefaultKey.previousVisitedLocation)
}
func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
guard locations.count > 0 else {
return
}
guard let location = locations.last else {
return
}
guard location.horizontalAccuracy > 0 else {
return
}
guard location.horizontalAccuracy < DISTANCE_LIMIT else { //DISTANCE_LIMIT is the value you have set for your distance filter
return
}
let previousLocationEncoded = UserDefaults.standard.object(forKey: UserDefaultKey.previousVisitedLocation) as? Data
if previousLocationEncoded == nil {
setCurrentLocation(location: location)
//do your tasks
} else {
let previousLocationDecoded = NSKeyedUnarchiver.unarchiveObject(with: previousLocationEncoded!) as! CLLocation
let distanceBetweenVisits = previousLocationDecoded.distance(from: location)
if distanceBetweenVisits > DISTANCE_LIMIT {
let timeIntervalBetweenVisits = location.timestamp.timeIntervalSince(previousLocationDecoded.timestamp)
guard timeIntervalBetweenVisits > 0 else {
return
}
setCurrentLocation(location: location)
//do your tasks
}
}
}
一起使用，它将自动在屏幕的右上方创建虚拟后退按钮。 （假设您从另一个屏幕上Scaffold小部件了。）
AppBar