SampleManager.m

- (NSDictionary *)verifyReceipt:(NSString *)base64Receipt isCoercion:(BOOL)isCoercion isSandbox:(BOOL)isSandbox {
  if (_completed || isCoercion) {
    if (base64Receipt) {
      NSURL *url = [NSURL URLWithString:isSandbox ? @"https://sandbox.itunes.apple.com/verifyReceipt" : @"https://buy.itunes.apple.com/verifyReceipt"];
      NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
      NSDictionary *requestContents = @{
                                        @"receipt-data": base64Receipt,
                                        @"password": SHARED_SECRET
                                        };
      ...