Swift Compare Set - facebook

Question

I try to check FB permissions, like this:
let permissions = ["user_friends", "public_profile"];
NSLog("Contains Permissions:%#", FBSDKAccessToken.currentAccessToken()
.permissions);
NSLog("Requested Permissions:%#", permissions);
if(!FBSDKAccessToken.currentAccessToken().permissions.contains(permissions)){
return false;
}else{
return true;
}
But it always returns false. Anyone an idea why ?
EDIT: Log output
Contains Permissions:{(
"user_friends",
"public_profile"
)}
2015-10-28 23:01:59.723: Requested Permissions:(
"user_friends",
"public_profile"
)

Answer 1

The contains() function you've used checks to see of any element of 'current Access Token' permissions is an array of permissions. It is always false because the token permissions are strings, NOT arrays of strings.
If the two arrays need to have exactly the same elements, then the absolute simplest code would be:
let permissions = ["user_friends", "public_profile"];
NSLog("Contains Permissions:%#", FBSDKAccessToken.currentAccessToken()
.permissions);
NSLog("Requested Permissions:%#", permissions);
tokenPermissions = FBSDKAccessToken.currentAccessToken().permissions as? [String]
return tokenPermissions != nil && tokenPermissions.sort().elementsEqual(permissions.sort())
You might first object to using sort(), perhaps as overkill, but otherwise you will be traversing the two lists of permissions multiple time so sort() ends up not being such a concern.
Another option is to iterate over the tokenPermissions and ensure that every one is in permissions. Like such:
for tokenPermission in tokenPermissions {
if !permissions.contains (tokenPermission) {
return false
}
}
return true
Or, if you got really ambitious and need to do a lot of sequence testing:
extension SequenceType {
public func any (#noescape predicate: (Self.Generator.Element) -> Bool) -> Bool {
for elt in self {
if predicate (elt) { return true }
}
return false
}
public func all (#noescape predicate: (Self.Generator.Element) -> Bool) -> Bool {
for elt in self {
if !predicate (elt) { return false }
}
return true
}
}
and then your code contains:
return tokenPermissions.all { permissions.contains ($0) }
And, finally, if the two arrays of permissions are actually sets of permissions then you can use
return Set(tokenPermissions).elementsEqual(Set(permissions))
So you've got a bunch of options.

Answer 2

What you are probably looking for is
let permissions = ["user_friends", "public_profile"]
let tokenPermissions = FBSDKAccessToken.currentAccessToken().permissions
NSLog("Contains Permissions:%#", tokenPermissions)
NSLog("Requested Permissions:%#", permissions)
guard let tokenPermissions = tokenPermissions as? Set<String> else {
return false
}
return tokenPermissions.isSupersetOf(permissions)
For the isSupersetOf(_:) syntax see Swift Collection Types, you need to cast the untyped NSSet into a Swift Set<String> for the function to work.

Answer 3

You can change:
if(!FBSDKAccessToken.currentAccessToken().permissions.contains(permissions))
to:
if FBSDKAccessToken.currentAccessToken().permissions.containsObject("user_friends") && FBSDKAccessToken.currentAccessToken().permissions.containsObject("public_profile")
Solution for alot of set, see example code:
let permisssion = NSSet(array:["user_friends", "public_profile"])
let test = NSSet(array: ["user_friends", "email","public_profile"])
if permisssion.isSubsetOfSet(test as Set<NSObject>) {
print("true")
} else {
print("false")
}