RangeReplaceableCollection

Converts the collection of RESPValueConvertible elements and appends them to the end of the array.

Adds the elements of a collection to this array, delegating the details of how they are added to the given closure.

When your closure will be doing more than a simple transform of the element value, such as when you’re adding both the key and value from a KeyValuePair, you should set the overestimatedCountBeingAdded to a value you do not expect to exceed in order to prevent multiple allocations from the increasing element count.

For example:

let pairs = [
    "MyID": 30,
    "YourID": 31
]
var values: [RESPValue] = []
values.add(contentsOf: pairs, overestimatedCountBeingAdded: pairs.count * 2) { (array, element) in
    // element is a (key, value) tuple
    array.append(element.0.convertedToRESPValue())
    array.append(element.1.convertedToRESPValue())
}

However, if you just want to apply a transform, you can do that more similarly to a call to the reduce methods:

let valuesToConvert = [...] // some collection of non-`RESPValueConvertible` elements, such as third-party types
let values: [RESPValue] = []
values.add(contentsOf: valuesToConvert) { (array, element) in
    // your transform and insert/append implementation
}

If the elementsToCopy has no elements, the closure is never called.