How to first 5 objects in Array with computed properties-CodePudding

My project uses an array of computed properties (hourly wages) from which I need to isolate/return only the first 5 objects (wages) in the array. (Note: I have simplified my code for the purpose of isolating this problem, but in so doing it may seem strange that this array is a computed property and not simply a variable. Please accept this oddity as it is necessary in my more complex, complete code.)

Research effort:

Here is my code with a variety of approaches attempting to accomplish the same result:

class EarningsViewModel: ObservableObject {
    
    var catWageArray: [Double] {
        [81,156,162,166,169,173,177,181,185,192,277,280,282,285,285,285,285,285,285,285,285,285,285,285,285,285,285,285,285,285,285,285,285,285,285,285,285,285,285,285,285]
    }

    var sliceCareerTest =  catWageArray.prefix(5)
    var sliceCareerTest2 =  catWageArray.prefix(upTo: 5)
    var sliceCareer: [Double] {
        catWageArray.prefix(5)}
    var sliceCareer2: [Double] {
        catWageArray.prefix(upTo: 5)}
    
    var n = 5
    var firstFiveSlice = catWageArray[0..<n]
    let firstFiveArray = Array(firstFiveSlice)

It seems to me that the sliceCareer computed property with the error "No 'prefix' candidates produce the expected contextual result type '[Double]'" may be the closest to the actual solution, but I don't understand why there the compiler cannot find prefix candidates.

CodePudding user response：

The proper way is prefix(5) but you have to create an array from the slice (aka SubSequence) and it must be a computed property.

On the other hand catWageArray can be a stored property

class EarningsViewModel: ObservableObject {
    
    var catWageArray: [Double] = [81,156,162,166,169,173,177,181,185,192,277,280,282,285,285,285,285,285,285,285,285,285,285,285,285,285,285,285,285,285,285,285,285,285,285,285,285,285,285,285,285]
    
    
    var sliceCareer: [Double] {
        Array(catWageArray.prefix(5))
    }
...