reference cycle 引用循环

标签：swift

在swift 里引用循环的造成，主要有两个方法，

1.类之间的引用

2.clourse 闭包引用

解决办法：

weak references and unowned references. 也就是weak，unowned

weak, 来修饰可选的，? 结尾的，如：var weak city: String ?

unowned 来修身 一直存在的。 var unowned city: String

• class Person {
  	letname: String
  	init(name:String) { self.name =name }
  	var apartment: Apartment?
  	deinit { println("\(name) is being deinitialized") }
  }
  class Apartment {
  	letnumber: Int
  	init(number:Int) { self.number =number }
  	weak var tenant: Person?
  	deinit { println("Apartment #\(number) is being deinitialized") }
  }

  weak 避免循环引用的例子

• class Customer {
  	letname: String
  	var card: CreditCard?
  	init(name:String) {
  	self.name = name
  	}
  	deinit { println("\(name) is being deinitialized") }
  }
  class CreditCard {
  	let number: UInt64
  	unowned let customer: Customer
  	init(number:UInt64, customer: Customer) {
  		self.number = number
  		self.customer = customer
  	}
  	deinit { println("Card #\(number) is being deinitialized") }
  }

  
  
  

• lazyvar someClosure: (Int,String) -> String = {
  [unownedself, weak delegate = self.delegate!] (index:Int, stringToProcess: String) -> String in
  // closure body goes here
  }

详情请看apple swift 文档

reference cycle 引用循环

标签：swift

原文地址：http://blog.csdn.net/wenluma/article/details/45844537