Thread 1: Fatal error: Index out of range In SwiftUI

Question

i am trying to make a small Social Media app. the friends and friendrequest gets stored as User in different arrays. But when i want to loop the array it an shows which user send a request it first works but when i accept the user and he is remove from the Array i am getting this error "Thread 1: Fatal error: Index out of range" i know its because the loop wants to loop to a index which doesn't exist anymore but how do i fix it ?

struct FriendsView: View {

@EnvironmentObject var appUser: User

var body: some View {
    
List {
    ForEach(0..<appUser.friendAnfrage.count) {
    durchlauf in
        SingleFriendView(user: appUser.friendAnfrage[durchlauf])
            }
        }
    }
}

class User: ObservableObject{

@Published var username: String = ""
@Published var name: String = ""
var password: String = ""
@Published var email: String = ""
@Published var beschreibung: String = ""
@Published var profilBild: UIImage?

@Published var friends = [User]()
@Published var friendAnfrage = [User]()
@Published var anfrageGesendet = [User]()

@Published var feed = [SinglePostView]()

func addFriend(friend: User,appUser: User) {
    friend.friendAnfrage.append(appUser)
    appUser.anfrageGesendet.append(friend)
    
}
func newFriend(newFriend: User) {
    friends.append(newFriend)
    
    for i in 0..<friendAnfrage.count {
        if friendAnfrage[i].username == newFriend.username {
            friendAnfrage.remove(at: i)
        }
    }
}
func friendAnfrage(friend: User,appUser: User) {
    appUser.friendAnfrage.append(friend)
}

func makePost(image: UIImage,appUser: User) {
    
    feed.append(SinglePostView(bild: image, ersteller: appUser))
    
    for i in 0..<friends.count {
        friends[i].feed.append(SinglePostView(bild: image, ersteller: appUser))
    }
}

}

have you debugged? in which line is it crashing? what's the value of the array before the for starts — Javier Heisecke
– Javier Heisecke, Commented Mar 2, 2022 at 20:34

jnpdx · Accepted Answer · 2022-03-02 20:37:56Z

1

ForEach with an index-based approach is dangerous in SwiftUI. Instead, make your model identifiable.

class User: ObservableObject, Identifiable {
  var id = UUID()
  //...

Then, change your loop:

ForEach(appUser.friendAnfrage) { item in
   SingleFriendView(user: item)
}

Unrelated to this exact issue, but generally SwiftUI does better with using a struct for a model instead of a class. If a User in friends is updated with your current code, because it's a nested ObservableObject, your View will not get automatically updated.

answered Mar 2, 2022 at 20:37

jnpdx

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5 Comments

schlachsahne Over a year ago

Where do i need the UUID for ?

schlachsahne Over a year ago

i Think i know, that i can better compare the User with each other right ?

jnpdx Over a year ago

Not you necessarily, but the system for sure. The ForEach loop uses it to identify each User.

jnpdx Over a year ago

I should note that if you have another way of identifying the user (which for a social media app, you should), you can use that as well -- you don't necessarily have to generate a random UUID. Just make sure it conforms to Identifiable or explicitly pass the identifier into the ForEach: ForEach(myCollection, id: \.myIdProperty)

schlachsahne Over a year ago

Sry mate i am very new to all that Stackoverflow stuff i think i just missclicked at some point but now your answer is marked as correctly. I didnt know i only can mark one Answer because both helped me much.

malhal · Accepted Answer · 2022-03-02 23:54:57Z

1

User should be a struct and ForEach isn't a traditional loop, it's a View that must be supplied identifiable data, e.g.

struct FriendsView: View {
    @EnvironmentObject var model: Model

    var body: some View {
        List {
            ForEach($model.users) { $user in
                SingleFriendView(user: $user)
            }
        }
    }
}

struct User: Identifiable{
    let id = UUID()
    var username: String = ""
    var friends: [UUID] = []
}

class Model: ObservableObject {
    @Published var users: [User] = []
}

edited Mar 2, 2022 at 23:54

answered Mar 2, 2022 at 23:09

malhal

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2 Comments

schlachsahne Over a year ago

Thank you for the answer, i have one question, i will try now to get the user into a struct but in my current class i have some Arrays which are set to published, when i change the class to a struct i get the Error "'wrappedValue' is unavailable: Published is only available on properties of classes" so i deleted the @Published keyword but then my functions addFriend and friendAnfrage are not working an having an error.

malhal Over a year ago

You can use mutating func in structs. For the friends you might be better using an array of IDs in the User struct.

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