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iOS

Tuan Do
Tuan Do
3,495 Points

Optional binding chaining

What's the difference between the two code snippets below or are they equivalent?

if let currentWeather = forecast?.currentWeather {
}

and

if let weatherForecast = forecast, let currentWeather = weatherForecast.currentWeather {
}

1 Answer

Hello:

Yes, they are equivalent, it's just that one is shorter than the other.

/* 
This one is going straight to the currentWeather,
by calling forecast?.currentWeather. This will return current weather
*/

if let currentWeather = forecast?.currentWeather {
}

and

/*
This one is doing a second step by first getting forecast 
and assigning it to weatherForecast, and then we get
currentWeather with the dot notation. "weatherForecast.currentWeather"
*/

if let weatherForecast = forecast, let currentWeather = weatherForecast.currentWeather {
}

Anything you don't understand, let me know and I can clarify it better.

Good luck

Tuan Do
Tuan Do
3,495 Points

That makes sense. Thanks!