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在Objective-C中向nil对象发送消息会crash吗？
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#IAGA3E
陌生人
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Opened this issue
2024-07-29 16:17
<p><span style="color: rgb(45, 45, 47); background-color: rgb(255, 255, 255); font-size: 16px;">不会。因为OC是动态语言，调用方法时会动态转成消息发送（如：objc_msgSend(test,@selector(go))）。当你向一个对象发送消息时，runtime会根据对象的isa找到其所属类，然后在该类的缓存方法列表、方法列表、其父类方法列表中寻找对应的方法运行，在发送消息时，objc_msgSend方法无返回值（void objc_msgSend(id self, SEL cmd, ... )）。 那么向nil对象发送消息，第一步就直接判空返回了，因此不会出现任何问题。</span></p>
<p><span style="color: rgb(45, 45, 47); background-color: rgb(255, 255, 255); font-size: 16px;">不会。因为OC是动态语言，调用方法时会动态转成消息发送（如：objc_msgSend(test,@selector(go))）。当你向一个对象发送消息时，runtime会根据对象的isa找到其所属类，然后在该类的缓存方法列表、方法列表、其父类方法列表中寻找对应的方法运行，在发送消息时，objc_msgSend方法无返回值（void objc_msgSend(id self, SEL cmd, ... )）。 那么向nil对象发送消息，第一步就直接判空返回了，因此不会出现任何问题。</span></p>
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