我正在处理一些遗留代码，这些代码在另一个内部调用一串块。我不时随机发生EXC_BAD_ACCESS崩溃，我无法弄清楚原因。
/
*
Description: Submit type card transaction to MCM server.
*/
- (void)submitTypeTransactionWithRequest:(ChargeRequest *)request completion:(void (^)(BOOL))completion {
//login to gateway to begin transaction
[self loginRoamServerWithCompletion:^(BOOL success) {
if (success) {
//make the payment
Payment *responsePayment = [self makePayment];
//if cvv is invalid, decline the transaction
[self voidTxnWhenCVV2OrAVSInvalid:responsePayment completion:^(BOOL isValidCVV) {
if (completion) {
completion(isValidCVV);
}
}];
}
}];
}
- (void)loginRoamServerWithCompletion:(void (^)(BOOL success))completion {
....
[self rpxLogonSuccessfulWithCompletion:^(BOOL success) {
if (completion) {
completion(success);
}
}];
}
- (void)voidTxnWhenCVV2OrAVSInvalid:(RpxPayment *)responsePayment completion:(void (^)(BOOL isValidCVV))completion {
//This method is now called second time in the flow
[self loginRoamServerWithCompletion:^(BOOL success) {
if (success) {
BOOL result = [self voidPayment];
if (completion) {
completion(result);
}
}
}];
}
- (void)rpxLogonSuccessfulWithCompletion:(void (^)(BOOL success))completion {
// at this point, when this method is called the second time => 'EXC_BAD_ACCESS'(completion = NULL)
BOOL result = [self login]
if (completion) {
completion(result);
}
}
这就是流程的工作原理。第一个电话是submitTypeTransactionWithRequest。然后调用loginRoamServerWithCompletion，然后调用rpxLogonSuccessfulWithCompletion。事务完成后，如果CVV无效，则调用voidTxnWhenCVV2OrAVSInvalid以使事务无效。这又会再次调用loginRoamServerWithCompletion，调用rpxLogonSuccessfulWithCompletion。当第二次调用rpxLogonSuccessfulWithCompletion时，代码会随着EXC_BAD_ACCESS错误而随机崩溃。根据堆栈跟踪，completion块的值为NULL。
