iPhone sdk paypal integration API

I have to integrate Paypal API into my iPhone App. I have included required libraries also. But I am getting only one following error.

"_SecTrustEvaluate", referenced from: -[PPMobileConnect connection:didReceiveAuthenticationChallenge:] in libPayPalMEP.a(PPMobileConnect.o) -[AdaptivePaymentsSOAP11BindingOperation connection:didReceiveAuthenticationChallenge:] i开发者_运维百科n libPayPalMEP.a(AdaptivePayments.o) ld: symbol(s) not found collect2: ld returned 1 exit status

How could I resolve this.

I include libxml2,libz also.

What i am missing?

Thanks karthik

Add the Security.framework. Hope it help!