[Solved] Find the mistake in this Swift code that attempts to save a Double value:let defaults = UserDefaults.standard defaults.set(3.14, forKeyName: "pi") let piValue = defaults.double(forKey: "pi") | iOS Swift

iOS Swift - Local Data Persistence

Find the mistake in this Swift code that attempts to save a Double value:

let defaults = UserDefaults.standard
defaults.set(3.14, forKeyName: "pi")
let piValue = defaults.double(forKey: "pi")

Adouble(forKey:) returns an optional and must be unwrapped

BUserDefaults cannot store Double values

CThe key "pi" must be declared as a constant

DThe method parameter should be 'forKey', not 'forKeyName'

Step-by-Step Solution

Solution:

Step 1: Check method signature
The correct method to set a value in UserDefaults is set(_:forKey:), not set(_:forKeyName:).
Step 2: Identify the error
Using 'forKeyName' causes a compile-time error because the method does not exist.
Step 3: Correct usage
Change to defaults.set(3.14, forKey: "pi") to fix the error.
Final Answer:
The method parameter should be 'forKey', not 'forKeyName' -> Option D
Quick Check:
Verify method signatures in documentation [OK]

Quick Trick: Use 'forKey' parameter name when setting values [OK]

Common Mistakes:

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Find the mistake in this Swift code that attempts to save a Double value: