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(→{{header|Swift}}: Update Swift entry to modern syntax and add another example) |
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=={{header|Swift}}== |
=={{header|Swift}}== |
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Swift has <code>Optional<T></code> type, where <code>nil</code> means a lack of value. |
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The closest thing in Swift are optional types. |
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<code>T?</code> is syntactic sugar for <code>Optional<T></code>. |
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<lang swift>var opt : Int? = nil // use "nil" to represent no value |
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<lang swift>let maybeInt: Int? = nil</lang> |
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opt = 5 // or simply assign a value to the optional type</lang> |
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To |
To just check if variable is nil, you can use <code>==</code> operator. |
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<lang swift>if |
<lang swift>if maybeInt == nil { |
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print("variable is nil") |
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} else { |
} else { |
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print("variable has some value") |
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}</lang> |
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Usually you want to access the value after checking if it's nil. To do that you use <code>if let</code> |
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<lang swift>if let certainlyInt = maybeInt { |
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print("variable has value \(certainlyInt)") |
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} else { |
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print("variable is nil") |
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}</lang> |
}</lang> |
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