However, because the reference is weak, the object that self points to could be deallocated while theblock is executing.You can eliminate this risk by creating a strong local reference to self inside the block: __weak BNREmployee *weakSelf = self; //…

转自:http://masteringios.com/blog/2014/03/06/avoid-strong-reference-cycles/ With the introduction of ARC, memory management became easier. However, even though you don’t have to worry about when to retain and release, there are still a few rules you ne…

You resolve a strong reference cycle between a closure and a class instance by defining a capture list as part of the closure’s definition. A capture list defines the rules to use when capturing one or more reference types within the closure’s body.…

  当在 Java 2 平台中首次引入 java.lang.ref 包,其中包含 SoftReference . WeakReference 和 PhantomReference 三个引用类,引用类的主要功能就是能够引用仍可以被垃圾收集器回收的对象.在引入引用类之前,我们只能使用强引用(strong reference).举例来说,下面一行代码显示的就是强引用 obj : Object obj = new Object(); obj 这个引用将引用堆中存储的一个对象.只要 obj 引用还存在,垃…

让我们长话短说.请参阅如下代码: - (IBAction)didTapUploadButton:(id)sender { NSString *clientID = @"YOUR_CLIENT_ID_HERE"; NSString *title = [[self titleTextField] text]; NSString *description = [[self descriptionTextField] text]; [[UIApplication sharedApplicati…

之前在看深入理解Java虚拟机一书中第一次接触相关名词,但是并不理解,只知道Object obj = new Object()类似这种操作的时候,obj就是强引用.强引用不会被gc回收直到gc roots不可达时.而对其他三个名词并不清楚,因为并没有被真正使用过.通过查看软引用,弱引用和虚引用的源码,可以看出这三个类都是继承自Reference. 一 概念 1.1软引用(SoftReference) 我理解的软引用的意思是,即使引用对象没有被使用了,gc也不会马上回收,而是只有当堆内存空间不够时…

版权声明:原创作品,谢绝转载!否则将追究法律责任. 一个Objective-c类定义了一个对象结合数据相关的行为.有时候,这使得他有意义的表达单个任务或者单元的行为.而不是集合的方法. blocks是语言的特性,我们可以在C C++ 和Objective-c看到,这允许你创建不同的代码片段,这代码片段可以通过在方法或者函数里调用如果他们有值.blocks是Objective- c的对象,意味着他们可以被添加到集合像数组和字典里.他们也有能力扑捉封闭范围值. 这章我们阐述怎么声明和引用blocks…

Here is a quick summary: A strong reference will keep the object it points to from being deallocated. Aweak reference will not. Thus instance variables and properties that are marked as weak are pointing atobjects that might go away. If this happens,…

Blocks are Objective-C objects, which means they can be added to collections like NSArray or NSDictionary. Block语法——无参数版本 定义(Block的值) ^{ NSLog(@"This is a block"); } 声明 void (^simpleBlock)(void); 类似int i; 赋值 simpleBlock = ^{ NSLog(@"This is…

Properties are either atomic or nonatomic, The difference has to do with multithreading. atomic is the default value. Properties are either readonly or readwrite. readwrite is the default value. Whenever you declare a property that points to an NSStr…