单例,类只能通过单例访问,不能自己构造
import Foundation
class Test {
var s:Int
private static let test = Test(s: 10)
static var shareInstance:Test{
return test
}
private init(s:Int){
self.s = s
}
}
var ss = Test.shareInstance
print(ss.s)
// private 属性作用域是Swift整个文件