class ca{
var vaName = "ca";
}
class cb: ca {
var vbName = "cb";
}
var item:ca = cb();
if let cbitem = item as? cb{
println(cbitem.vbName);
}
原文链接：https://www.f2er.com/swift/326909.html
class ca{
var vaName = "ca";
}
class cb: ca {
var vbName = "cb";
}
var item:ca = cb();
if let cbitem = item as? cb{
println(cbitem.vbName);
}
原文链接：https://www.f2er.com/swift/326909.html