Swift 面试题与答案
Test your skills through the online practice test: Swift Quiz Online Practice Test
问题 6. Explain optionals in Swift.
Optionals are a type in Swift that represents either a wrapped value or nil, indicating the absence of a value.
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问题 7. What is the difference between 'let' and 'var' in Swift?
'let' is used to declare constants, and 'var' is used to declare variables.
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问题 8. What is a closure in Swift?
A closure is a self-contained block of functionality that can be passed around and used in your code.
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问题 9. Explain the difference between a value type and a reference type in Swift.
A value type is copied when it's assigned to a new variable or passed as an argument, while a reference type refers to the same instance of the data.
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问题 10. What is ARC (Automatic Reference Counting) in Swift?
ARC is a memory management feature in Swift that automatically tracks and manages the memory usage of your app.
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用户评价最有帮助的内容：
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- Explain optionals in Swift.
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