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So, I have a for-loop that looks similar to this:
for var i = 0; i < results.count ; i += 1 { if (results[i] < 5) { results.removeAtIndex(i) i -= 1 } } This used to work. But when I changed it to the preferred Swift 3.0 syntax:
for var i in 0..<results.count { if (results[i] < 5) { results.removeAtIndex(i) i -= 1 } } I get an array IOOBE exception because it doesn't re-check the count and continues on until the original results.count.
How do I fix this? It works now, but I don't want to get into trouble in the future.
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We can use iteration with a for loop to visit each element of an array. This is called traversing the array. Just start the index at 0 and loop while the index is less than the length of the array.
To replace an element with another value in Swift Array, get the index of the match of the required element to replace, and assign new value to the array using the subscript.
for Loop with where Clause In Swift, we can also add a where clause with for-in loop. It is used to implement filters in the loop. That is, if the condition in where clause returns true , the loop is executed. In the above example, we have used a for-in loop to access each elements of languages .
While the solution making use of filter is a fine solution and it's more Swift-ly, there is another way, if making use of for-in is, nonetheless, still desired:
func removeBelow(value: Int) { var results = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] for i in (0 ..< results.count).reversed() { if (results[i] < value) { results.remove(at: i) } } print(results) } removeBelow(value: 5) Result:
[5, 6, 7, 8, 9, 10] The problem with removeAtIndex within the loop is that it will not cause the array to re-index itself in-place and thus causing an array out of bounds exception due to count not being updated.
By traversing backwards, the out of bounds exception can thus be avoided.
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