Free App-Development-with-Swift-Certified-User Questions Attempt

This question is from Swift Programming Language , especially the domains for Optional types , safe and unsafe unwrapping , and control flow . The code uses the ternary conditional operator :

nextApplePhone.releaseDate != nil ? _____

In Swift, the ternary operator follows this structure:

condition ? valueIfTrue : valueIfFalse

So if nextApplePhone.releaseDate != nil is true, the expression must return the new release date. If it is false, it must keep lastReleaseDate unchanged. That means the missing part must be:

nextApplePhone.releaseDate! : lastReleaseDate

which is option D .

This works because nextApplePhone.releaseDate is declared as String?, so it is an optional. Once the condition confirms it is not nil, the code force-unwraps it with ! to access the underlying String value. If the optional is nil, the expression returns lastReleaseDate instead. Apple’s Swift documentation describes the ternary conditional operator as a shortcut for choosing one of two expressions based on a condition, and it explains that force unwrapping with ! accesses an optional’s wrapped value when you know it is not nil.

The other options are incorrect because they reverse the true/false logic, omit the needed unwrap, or contain invalid identifiers. Therefore, the correct completion is D .

This question belongs to Swift Programming Language , specifically the domain on functions , including internal and external parameter names and default parameter values .

The function is defined as:

func rightSum(_ num1: Int, by num2: Int, and num3: Int = 25) - > Int {

return num1 + num2 + num3

}

This means:

the first parameter uses _, so it has no external label

the second parameter must use the external label by

the third parameter must use the external label and

the third parameter also has a default value of 25, so it may be omitted

Now evaluate each option:

A is invalid because it uses num2: instead of the required external label by:

B is valid because it correctly uses no label for the first argument, then by: and and:

C is invalid because the first parameter cannot be called with num1: since the external label is omitted with _

D is valid because it correctly passes the first argument unlabeled and the second with by:, while omitting the third argument so Swift uses the default value 25

E is invalid because it uses num1: and num2: instead of the required calling syntax

So the two correct function calls are B and D .

Comprehensive and Detailed Explanation From App Development with Swift domains:

This question falls under Swift Programming Language , specifically the domain for managing data using collection types , with emphasis on dictionaries . In Swift, a dictionary stores data as key-value pairs , so in this example the country name is the key and the capital city is the value. To add a new entry, Swift supports two standard approaches. The first is subscript assignment , which is shown in option C : capitalCities[ " Italy " ] = " Rome " . Apple’s documentation explains that you can add a key-value pair to a dictionary by assigning a value for a new key through the dictionary subscript.

The second correct approach is option E : capitalCities.updateValue( " Rome " , forKey: " Italy " ). Apple documents that updateValue(_:forKey:) updates the value for an existing key, or adds a new key-value pair if the key does not already exist . That makes it equally valid for inserting " Italy " : " Rome " into the dictionary.

The incorrect options fail for different reasons. A reverses the key and value, making " Rome " the key and " Italy " the value. B is wrong because append is used with arrays, not dictionaries. D is not the standard valid insertion syntax for Swift dictionaries in this context; Swift’s documented mutation approaches here are subscript assignment and updateValue. Therefore, the two correct answers are C and E .

This question belongs to Swift Programming Language , specifically the domain covering structs, properties, methods, and initializers .

A computed property does not store a value directly. Instead, it returns a value calculated from other data. That is why description is a computed property: it returns a string based on content.

A memberwise initializer is automatically provided by Swift for structs when their stored properties are initialized through parameters. So Document(content: " Greetings! " ) is using the struct’s memberwise initializer.

A type property belongs to the type itself rather than to an instance. In Swift, static var docCount = 0 is a type property because it is declared with static.

An instance method is a function that belongs to an instance of the struct or class. The display() method uses the instance’s content, so it is an instance method.

A type method is a method declared with static and belongs to the type itself. So static func increment() is a type method because it changes the shared type property docCount.