runDelayed method
延时执行
Implementation
String runDelayed(
Function runnable, {
Duration delay = Duration.zero,
String? tag,
}) {
assert(delay.inMilliseconds >= 0, 'delay must >= 0.');
// 检查标签
tag = _checkedTag(tag);
// 启动线程
var thread = Timer(delay, () {
// 执行完毕并移除线程
runnable.call();
removeThread(tag!);
});
// 缓存信息
_threads.put(tag, thread);
return tag;
}