Find element in an array of object

Question

I created an array of objects:

var fullMonthlyList = [SimulationMonthly]()

The class here:

class SimulationMonthly {
    var monthlyMonthDuration: NSNumber = 0
    var monthlyYearDuration: NSNumber = 0
    var monthlyFullAmount: NSNumber = 0
    var monthlyAmount: Int = 0

    init(monthlyMonthDuration: NSNumber, monthlyYearDuration: NSNumber, monthlyFullAmount: NSNumber, monthlyAmount: Int){
        self.monthlyMonthDuration = monthlyMonthDuration
        self.monthlyYearDuration = monthlyYearDuration
        self.monthlyFullAmount = monthlyFullAmount
        self.monthlyAmount = monthlyAmount
    }
}

I just did append to populate it, now I want to find for example if they're an existing value, for example monthlyAmount equals to "194" by search in the array, how can I do ? I have tried filter and contains but I get errors.

What I've tried:

if self.fullMonthlyList.filter({ $0.monthlyAmount == self.monthlyAmount.intValue }) { ... }

Error:

Cannot invoke 'filter' with an argument list of type '((SimulationMonthly) throws -> Bool)'

"I have tried filter and contains but I get errors." Can you show us what you did and which error did you get? — Eendje
– Eendje, Commented Dec 13, 2016 at 16:12
@Eendje for if self.fullMonthlyList.filter({$0.monthlyAmount == self.monthlyAmount.intValue}){ I get: Cannot invoke 'filter' with an argument list of type '((SimulationMonthly) throws -> Bool)' — Ben
– Ben, Commented Dec 14, 2016 at 8:21

Keiwan · Accepted Answer · 2016-12-13 18:43:33Z

3

You can do:

if let sim = fullMonthlyList.first(where: { $0.monthlyAmount == 194 }) {
    // Do something with sim or print that the object exists...
}

This will give you the first element in your array where monthlyAmount equals 194.

If you want all elements with that condition, you can use filter:

let result = fullMonthlyList.filter { $0.monthlyAmount == 194 }

If you don't need the object at all but you just want to know if one exists, then contains would be enough:

let result = fullMonthlyList.contains(where: { $0.monthlyAmount == 194 })

edited Dec 13, 2016 at 18:43

answered Dec 13, 2016 at 16:15

Keiwan

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1 Comment

Alexander Over a year ago

I recommend you use trailing closure syntax, though I can see the value of having where: for demonstrative purposes

Phillip Mills · Accepted Answer · 2016-12-13 17:05:31Z

1

Here's a simple playground example of filtering objects based on matching a property. You should be able to expand it to your situation.

class Item {
    var value: Int

    init(_ val: Int) {
        value = val
    }
}

var items = [Item]()
for setting in 0..<5 {
    items.append(Item(setting))
}

func select(_ with: Int) -> [Item] {
    return items.filter { $0.value == with }
}

let found = select(3)

edited Dec 13, 2016 at 17:05

answered Dec 13, 2016 at 16:32

Phillip Mills

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3 Comments

Alexander Over a year ago

I'd recommend against writing a trivial function like select() in your example. It doesn't abstract much, but still adds an unnecessary layer of abstraction.

Phillip Mills Over a year ago

Rollback. (If you're going to edit an answer to match your coding style, at least change it to something that compiles.)

Alexander Over a year ago

Whoops, that should've been (0..<5).map(Item.init)

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