Check each value inside a nested array of a dictionary Swift - arrays

Question

I know this question might seem obvious to some, but i can't get around a proper solution.
I have a dictionary
someDict = [String : [Int]]
Also i have an Integer variable and a string
var someNumber = Int()
var someString = String()
My goal is to compare if someString = someDict key and if yes - compare every Int value inside it's nested array to someNumber (check whether it's smaller or bigger and give some output).
Thank you!

Answer 1

First you look for the key in the dictionary that matches the one you're after — so we loop through all the keys.
Then, once we find a match, we loop through all the contents of that keys value. In this case, its our array of numbers.
let someDict = ["matchingString" : [6,7,5,4]]
var someNumber = 5
var someString = "matchingString"
for (someDictKey, numbers) in someDict {
if someDictKey == someString {
// Key Found
for number in numbers {
if number == someNumber {
// Number Found
} else {
// no matching number found
}
}
} else {
// No matching key found
}
}
Try it in a playground.

Answer 2

You can make use of optional chaining, without the need to explicitly loop over the dictionary entries.
var someDict = [String : [Int]]()
someDict["SomeString"] = [Int](1...5)
let someString = "SomeString"
let someNumber = 2
if someDict[someString]?.contains(someNumber) ?? false {
print("Dict value array for key '\(someString)' contains value \(someNumber).")
}
else {
print("Dict value array for key '\(someString)' does not contain value \(someNumber).")
}
/* Prints: Dict value array for key 'SomeString' contains value 2. */
If we're dealing with a huge dictionary, looping over all dictionary entries kind of defeats the purpose of dictionaries O(1) hash value lookup (i.e., just attempting to access the key directly).

Answer 3

Try this:
var someDict = [String : [Int]]()
someDict["a"] = [1, 2, 3]
someDict["b"] = [4, 5, 6]
var str = "a"
var number = 3
for (key, value) in someDict {
if key == str {
for num in value {
if num == number {
print("matched")
} else {
print("Oops")
}
}
} else {
print("nope")
}
}

Answer 4

You can simply ask the dictionary for the key you're interested into, and enumerate within the corresponding object:
// this helps us get rid of having to unwrap someDict["someString"] first
for intVal in someDict["someString"] ?? [Int]() {
print(intVal < someNumber ? "smaller" : "not smaller")
}
Or, if your interested on finding the numbers smaller that someNumber, you can use the filtering support:
let smallerNumbers = (someDict[someString] ?? [Int]()).filter({$0 < someNumber})