Combining UnitMass and UnitLength arrays

Question

I'm trying to combine two measurement arrays:

var unitMasses: [UnitMass] {
    return [.milligrams, .grams, .kilograms, .ounces, .pounds]
}

var unitLengths: [UnitLength] {
    return [.centimeters, .decimeters, .meters]
}

into one:

var units: [AnyObject] {
    // This works:
    return [unitMasses].flatMap{$0}
    // But I've tried the following and this doesn't:
    //return ([unitMasses as AnyObject] + [unitVolumes as AnyObject]).flatMap{$0}
}

I want to be able able to to access the .symbol attribute of the elements in the units variable:

var symbols: [String] {
    return units.map({ unit in unit.symbol })
}

Thanks.

@OlegGordiichuk I thought that they were classes? "The NSUnitVolume class is an Dimension subclass that encapsulates units of measure for volume." — ajrlewis, Mar 16 '17 at 09:34

Oleg Gordiichuk · Accepted Answer · 2017-03-16T09:52:41.667

2

From my point of view this way is quite more straight forward.I do not see any needs to merge arrays before.

var symbols = unitMasses.map({$0.symbol})
symbols += unitLengths.map({$0.symbol})

print(symbols) // ["mg", "g", "kg", "oz", "lb", "cm", "dm", "m"]

edited Mar 16 '17 at 09:52

answered Mar 16 '17 at 09:44

Oleg Gordiichuk

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1

I'd also point out that the map can be done like... `unitMasses.map{ $0.symbol }` :D – Fogmeister Mar 16 '17 at 09:51
@Fogmeister Thanks - not sure that convention is for me ...! A bit ugly – ajrlewis Mar 16 '17 at 10:00
@Oleg Gordiichuk Thanks! – ajrlewis Mar 16 '17 at 10:00

score 1 · Answer 2 · answered Mar 16 '17 at 10:01

The accepted answer works well. For completeness, this is how I used it:

var units: [Dimension] {
    return unitMasses.map({ unit in unit }) + unitLengths.map({ unit in unit })
}

var symbols: [String] {
    return units.map({ unit in unit.symbol })
}

Combining UnitMass and UnitLength arrays

2 Answers2