I'm doing some operations like sorting, filter and grouped by some attributes of arrays object.

I'm adding objects of a filtered array in to another array like:

```
arrGroup.append(contentsOf: filteredArray)

```

My question is: will all of the objects maintain the same sorted order in the array every time, with 100% certainty?

Logically, will it add the object like

```
for object in filteredArray {
    arrGroup.append(object) 
}

```

**or** 

```
for index in 0...filteredArray.count {
    let object = filteredArray[index]
    arrGroup.append(object)
}

```

For me, all are same, just difference in CPU cycle at run time. But my friend says that I should go with last option. Technically I'm getting same result for all three every time I debug my code.

Your suggestion please.