简单小例子，可以简单的看下逻辑的书写，希望能对刚接触objective－c的理解和帮助哦，希望会对你们有帮助哦，很简单和适合初学者使用-Simple example, you can simply look logical writing, hope to understand and help new to objective-c Oh, will you help Oh, very simple and suitable for beginners