CODEWITHSUNDEEP
iosswift
Vamsi S
Vamsi S

Reputation: 269

App crashes within for loop in swift 3

Here I am just getting array count and using for loop but got crashed at let arr = arrayAdaptor[i] this line after completing my array count don't know why it's crashing can anyone help me how to resolve this 

var arrayAdaptor  = [Struct_Row_Rating]()

for i in 0...arrayAdaptor.count {
            let arr = arrayAdaptor[i]
            let number = arr.row
            let row = number + 1
            dict.updateValue("\(arr.rating)", forKey: "\(row)")
            print(dict)
        }
struct Struct_Row_Rating {
    var row: Int
    var rating: Double

    init(row: Int , rating: Double) {
        self.row = row
        self.rating = rating

    }}

Upvotes: 1

Views: 852

Answers (5)

Ankit Sharma
Ankit Sharma

Reputation: 91

You can also iterate loop by 'map' function:

    let _ = arrayAdaptor.map({ adaptor in

            let number = adaptor.row
            let row = number + 1

            dict.updateValue("\(adaptor.rating)", forKey: "\(row)")
            print(dict)
     })

Upvotes: 0

Salman Ghumsani
Salman Ghumsani

Reputation: 3657

Why you are using 0...arrayAdaptor.count range style avoid it and Simply Use enumerated() of an Array:

for (_,value) in arrayAdaptor.enumerated() {
      let number = value.row
      let row = number + 1
      dict.updateValue("\(arr.rating)", forKey: "\(row)")
      print(dict)
 }

If you don't want any index to try with this:

for value in arrayAdaptor { 
      let number = value.row
      let row = number + 1
      dict.updateValue("\(arr.rating)", forKey: "\(row)")
      print(dict)
}

See this

Upvotes: 6

Jack
Jack

Reputation: 14329

From Swift 4 you can use One sided ranges.

i... is favored over i..< because the latter is ugly. We have to pick one, two would be redundant and likely to cause confusion over which is the "right" one. Either would be reasonable on pedantic correctness grounds – (i as Int)... includes Int.max consistent with ..., whereas a[i...] is interpreted as a[i..<a.endIndex] consistent with i..<.

Example:

var names = ["Jack", "New", "peter"]
        let first = names[0...]
        let second = names[..<names.count]
        print(first)//prints ["Jack", "New", "peter"]
        print(second)//prints ["Jack", "New", "peter"]

Upvotes: 1

Hexfire
Hexfire

Reputation: 6058

One of the options not mentioned in the answers is forEach approach.

arrayAdaptor.forEach { item in
   print(item)
}

or 

arrayAdaptor.forEach { 
   print($0) // without named parameter
}

// Your case:

arrayAdaptor.forEach { item in
    let arr = item
    let number = item.row
    let row = number + 1
    dict.updateValue("\(arr.rating)", forKey: "\(row)")
    print(dict)
}

This is pretty much the same as the handy for..in mentioned in vadian's answer:

for arr in arrayAdaptor { ... }

Upvotes: 1

vadian
vadian

Reputation: 285072

The operator ... exceeds the range of the array. You have to write

for i in 0..<arrayAdaptor.count

or

for i in 0...arrayAdaptor.count - 1

Basically don't use these index based for loops in Swift at all.

Use Fast Enumeration:

for arr in arrayAdaptor {

and if you really need the index 

for (index, arr) in arrayAdaptor.enumerated() {

Upvotes: 8

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