• KVC的全称是Key-Value Coding，俗称“键值编码”，可以通过一个key来访问某个属性
  • 常见的API有
    • 设置
        • (void)setValue:(id)value forKeyPath:(NSString *)keyPath;
        • (void)setValue:(id)value forKey:(NSString *)key;
    • 取值
        • (id)valueForKeyPath:(NSString *)keyPath;
        • (id)valueForKey:(NSString *)key;
  • 常见KVC引发的报错

    • 设置value：未找到对应的key

      • NSUnknownKeyException：[<Person 0x10131aee0> setValue:forUndefinedKey:]
      Terminating app due to uncaught exception 'NSUnknownKeyException',
 reason: '[<Person 0x10131aee0> setValue:forUndefinedKey:]:this class is not key value coding-compliant for the key age1.'

    • 获取value：未找到对应的key

      • NSUnknownKeyException：[<Person 0x100735bb0> valueForUndefinedKey:]
      Terminating app due to uncaught exception 'NSUnknownKeyException', 
reason: '[<Person 0x100735bb0> valueForUndefinedKey:]: this class is not key value coding-compliant for the key age2.'