Closures, higher-order functions, throws and try, Result, ARC, retain cycles and weak or unowned references.
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- What is a closure in Swift?
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A self-contained block of functionality that captures and stores references to variables and constants from its surrounding context.- What is the simplest closure syntax?
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{ parameters in statements }- What does it mean for a closure to capture a value?
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The closure stores a reference to a variable or constant from its surrounding scope, allowing access even after the scope ends.- What is an escaping closure?
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A closure called after the function it was passed to returns, escaping the function's scope.- What does @escaping indicate?
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A closure parameter that may be called after the function returns, so it escapes the function's scope.- What is a trailing closure?
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A closure passed as the last argument to a function, written outside the parentheses for readability.- How do closures differ from named functions?
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Closures are unnamed blocks that capture surrounding context; functions are named and do not capture context by default.- Can closures have explicit return types?
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Yes, written as { (parameters) -> ReturnType in statements }.- What is an autoclosure?
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A closure automatically created to wrap an expression, marked with @autoclosure, allowing you to omit braces.- What is a non-escaping closure?
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A closure guaranteed to be called before the function returns, unable to escape the function's scope (the default).- What is a higher-order function?
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A function that takes one or more functions as arguments or returns a function as its result.- What does map do?
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Transforms each element in a collection using a closure and returns a new array with the transformed elements.- What does filter do?
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Returns a new array containing only the elements that satisfy the condition in the closure.- What does reduce do?
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Combines all elements into a single value by applying a closure that takes an accumulated value and the next element.- What does sorted do?
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Returns a new array with elements sorted according to the closure that compares two elements.
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