Thread 1: "[<number_random.ViewController 0x128608960> setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key random."

when I run my program this message appears

Thread 1: "[&lt;number_random.ViewController 0x128608960&gt; setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key random."
 
 
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