我尝试构建项目时遇到此错误：
Undefined symbols for architecture i386:
“_xmlParseMemory”,referenced from:
-[AdaptivePaymentsSOAP11Binding_CancelPreapproval connectionDidFinishLoading:] in libPayPalMPL.a(AdaptivePayments.o)
-[AdaptivePaymentsSOAP11Binding_ConfirmPreapproval connectionDidFinishLoading:] in libPayPalMPL.a(AdaptivePayments.o)
-[AdaptivePaymentsSOAP11Binding_ConvertCurrency connectionDidFinishLoading:] in libPayPalMPL.a(AdaptivePayments.o)
-[AdaptivePaymentsSOAP11Binding_ExecutePayment connectionDidFinishLoading:] in libPayPalMPL.a(AdaptivePayments.o)
-[AdaptivePaymentsSOAP11Binding_GetPaymentOptions connectionDidFinishLoading:] in libPayPalMPL.a(AdaptivePayments.o)
-[AdaptivePaymentsSOAP11Binding_PaymentDetails connectionDidFinishLoading:] in libPayPalMPL.a(AdaptivePayments.o)
-[AdaptivePaymentsSOAP11Binding_Pay connectionDidFinishLoading:] in libPayPalMPL.a(AdaptivePayments.o)
…