Thread 1: Exception: "[<UIViewController 0x7f8fbd7103d0> setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key startBtn." code example

Example: uncaught exception 'NSUnknownKeyException', reason: '[ setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key

//Go to this link :)
//https://stackoverflow.com/questions/38308329/swift-setvalueforundefinedkey-this-class-is-not-key-value-coding-compliant-f