Service unavailable error (CKError Code 6) in CKContainer requestApplicationPermission - ios

Question

I am trying to read user's name from their iCloud account using CloudKit as below
CKContainer *container = [CKContainer defaultContainer];
[container accountStatusWithCompletionHandler:^(CKAccountStatus accountStatus, NSError * _Nullable error) {
if (accountStatus == CKAccountStatusAvailable) {
[container requestApplicationPermission:CKApplicationPermissionUserDiscoverability completionHandler:^(CKApplicationPermissionStatus applicationPermissionStatus, NSError * _Nullable error) {
if (applicationPermissionStatus == CKApplicationPermissionStatusGranted) {
[container fetchUserRecordIDWithCompletionHandler:^(CKRecordID * _Nullable recordID, NSError * _Nullable error) {
if (!error && recordID) {
[container discoverUserIdentityWithUserRecordID:recordID completionHandler:^(CKUserIdentity * _Nullable userInfo, NSError * _Nullable error) {
NSLog(#"UserInfo: %# Error: %#", userInfo, error);
}];
}
}];
}
}];
}
}];
but every time requestApplicationPermission fails with Service Unavailable error and status is CKApplicationPermissionStatusCouldNotComplete. I am not sure what am I doing wrong here. I tried it with multiple devices and accounts but still result is same. I have tried disabling and enabling CloudKit in capabilities as was suggested in some places but no luck. Is there any information that I need to configure which I am missing. Below is how my iCloud capability looks

Answer 1

Well it turns out I needed to call statusForApplicationPermission: before calling requestApplicationPermission. It was really baffling that just because I did not check the permission status, the permission request was failing. That too with Service UnAvailable error. Here is the code that works(not very elegant):
CKContainer *container = [CKContainer defaultContainer];
[container accountStatusWithCompletionHandler:^(CKAccountStatus accountStatus, NSError * _Nullable error) {
if (accountStatus == CKAccountStatusAvailable) {
[container statusForApplicationPermission:CKApplicationPermissionUserDiscoverability completionHandler:^(CKApplicationPermissionStatus applicationPermissionStatus, NSError * _Nullable error) {
if (applicationPermissionStatus==CKApplicationPermissionStatusInitialState || applicationPermissionStatus==CKApplicationPermissionStatusGranted) {
[container requestApplicationPermission:CKApplicationPermissionUserDiscoverability completionHandler:^(CKApplicationPermissionStatus applicationPermissionStatus, NSError * _Nullable error) {
if (applicationPermissionStatus == CKApplicationPermissionStatusGranted) {
[container fetchUserRecordIDWithCompletionHandler:^(CKRecordID * _Nullable recordID, NSError * _Nullable error) {
if (!error && recordID) {
[container discoverUserIdentityWithUserRecordID:recordID completionHandler:^(CKUserIdentity * _Nullable userInfo, NSError * _Nullable error) {
NSLog(#"UserInfo: %# Error: %#", userInfo, error);
}];
}
}];
}
}];
}
}];
}
}];