编程札记:peformSelector一点认识

 performSelector消息会将讲接收者的引用计数retainCount加一

 

NSUInteger c = [self retainCount];//c为1

[self performSelector:@selector(process_one_job_item) withObject:nil afterDelay:0];

c = [self retainCount];//c为2

这将确保process_one_job_item运行时self不为空

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