验证iOS 6和7中的购买收据

Question

我正在使用以下代码验证应用内购买收据:

- (void) completeTransaction:(SKPaymentTransaction*) transaction
{   
    NSData* receipt = nil;

    // 1. Attempt <app receipt> first (iOS 7.x)

    NSBundle* mainBundle = [NSBundle mainBundle];

    if ([mainBundle respondsToSelector:@selector(appStoreReceiptURL)]) {

        NSURL* appStoreReceiptURL = [mainBundle appStoreReceiptURL]; // <- CRASH

        receipt = [NSData dataWithContentsOfURL:appStoreReceiptURL];
    }

    // 2. Fallback to <transaction receipt> (iOS < 7.0)
    if (!receipt) {    
        receipt = [transaction transactionReceipt];
    }

    // 3. Have server verify it with iTunes:    
    [self verifyReceipt:receipt forTransaction:transaction];
}

在iOS 6设备上,执行在该行停止NSURL* appStoreReceiptURL = [mainBundle appStoreReceiptURL];并且控制台吐出:

-[NSBundle appStoreReceiptURL]: unrecognized selector sent to instance 0x208492d0

我错过了什么吗？不-respondsToSelector:应该照顾这个吗？我必须回头直接检查操作系统版本吗？

Answer 1

是的,你应该在这个appStoreReceiptURL方法的情况下直接检查版本号. appStoreReceiptURL

在iOS中,使用以下代码检测此方法是否可用:

if (floor(NSFoundationVersionNumber) <= NSFoundationVersionNumber_iOS_6_1) {
   // Load resources for iOS 6.1 or earlier
} else {
   // Load resources for iOS 7 or later
}

注意:这里不能使用使用respondsToSelector:方法进行弱链接的一般最佳实践.在iOS 7之前,方法(appStoreReceiptURL)是作为私有API实现的,但该实现称为doesNotRecognizeSelector:方法.

参考:NSBundle类参考