Swift定义单例

struct SomeStructure {
static var storedTypeProperty = "Some value."
static var computedTypeProperty: Int {
return 1
}
class var overrideableComputedTypeProperty: Int {
return 107
}
}

class singletonClass {
static let sharedInstance = singletonClass()
private init() {} // 这就阻止其他对象使用这个类的默认的'()'初始化方法
}