of<S> static method
从 Widget tree 中获取 AppStartBloc 实例
Implementation
static AppStartBloc<S> of<S>(BuildContext context) {
final _AppStartInherited<S>? inherited =
context.dependOnInheritedWidgetOfExactType<_AppStartInherited<S>>();
assert(inherited != null, 'AppStartScope<$S> not found in widget tree.');
return inherited!.bloc;
}