近日在專案內購中遇到“您已經購買了此程式內購買（In App Purchase）專案，但尚未下載”的問題，查閱google和百度各種文章，沒找到合適的解決方案，折騰一整天，終於解決，解決方案貼出來，供大家參考。也是為了驗證這個方案的正確性。歡迎拍磚！

首先說說出現這個問題的原因，一般是購買成功後業務邏輯出了問題（或者是邏輯依賴網路，網路出了問題），沒有成功呼叫finishTransaction,看如下程式碼：

- (void)paymentQueue:(SKPaymentQueue *)queue updatedTransactions:(NSArray *)transactions {
	for(SKPaymentTransaction *transaction in transactions) {
		switch (transaction.transactionState) {
				
			case SKPaymentTransactionStatePurchasing:
				// Item is still in the process of being purchased
				break;
				
			case SKPaymentTransactionStatePurchased:
				// Item was successfully purchased!
				[self completeTransaction:transaction];//這兒出了問題拋異常，導致下面一句程式碼沒執行
				
				[[SKPaymentQueue defaultQueue] finishTransaction:transaction];
				break;
				
			case SKPaymentTransactionStateRestored:
				// Return transaction data. App should provide user with purchased product.
                [self restoreTransaction:transaction];
                
				[[SKPaymentQueue defaultQueue] finishTransaction: transaction];
				break;
				
			case SKPaymentTransactionStateFailed:
				// Purchase was either cancelled by user or an error occurred.
				[self failedTransaction:transaction];
                
				// Finished transactions should be removed from the payment queue.
				[[SKPaymentQueue defaultQueue] finishTransaction: transaction];
				break;
		}
	}
}
 

所以每次再次購買的時候就回提示“”您已經購買了此程式內購買（In App Purchase）專案，但尚未下載”。既然問題已經找到，那麼我們就來解決問題吧，問題的關鍵就是把上次未成功處理的transaction處理完，那麼怎麼獲得上次未處理完的transaction呢，可以通過[[SKPaymentQueue defaultQueue] transactions]獲取，我自己是在使用者再次購買行為的時候去做的，當用戶再次購買的時候，先檢查是否有之前未完成的交易，關鍵程式碼如下：

NSArray* transactions = [SKPaymentQueue defaultQueue].transactions;
if (transactions.count > 0) {
	//檢測是否有未完成的交易
	SKPaymentTransaction* transaction = [transactions firstObject];
	if (transaction.transactionState == SKPaymentTransactionStatePurchased) {
		[self completeTransaction:transaction];
		[[SKPaymentQueue defaultQueue] finishTransaction:transaction];
                return;
	}
}
 

ok，搞定！