Unity 4.7 Admob iOS link error

I import Admob plugin (Google Mobile Ads SDK) and export the Xcode project. When compile the project, there are some link error like this:

Undefined symbols for architecture arm64: "__GADShowInterstitialAd", referenced from: IOSAdMobController_GADShowInterstitialAd_m423384108_0 in Bulk_Assembly-CSharp_0.o (maybe you meant: IOSAdMobControllerGADShowInterstitialAd_m423384108_0) "_GADReportPurchaseStatus", referenced from: IOSAdMobController_GADReportPurchaseStatus_m1317586520_0 in Bulk_Assembly-CSharp_0.o (maybe you meant: IOSAdMobControllerGADReportPurchaseStatus_m1317586520_0) "_GADLoadInterstitialAd", referenced from: IOSAdMobController_GADLoadInterstitialAd_m_1495118827_0 in Bulk_Assembly-CSharp_0.o (maybe you meant: IOSAdMobControllerGADLoadInterstitialAd_m_1495118827_0) "_GADStartInterstitialAd", referenced from: IOSAdMobController_GADStartInterstitialAd_m1533596851_0 in Bulk_Assembly-CSharp_0.o (maybe you meant: IOSAdMobControllerGADStartInterstitialAd_m1533596851_0) "_GADDestroyBanner", referenced from: IOSAdMobController_GADDestroyBanner_m1819346905_0 in Bulk_Assembly-CSharp_0.o (maybe you meant: IOSAdMobControllerGADDestroyBanner_m1819346905_0) "_GADSetBirthday", referenced from: IOSAdMobController_GADSetBirthday_m61859954_0 in Bulk_Assembly-CSharp_0.o (maybe you meant: IOSAdMobControllerGADSetBirthday_m61859954_0) "_GADAddTestDevices", referenced from: IOSAdMobController_GADAddTestDevices_m_1032479912_0 in Bulk_Assembly-CSharp_0.o (maybe you meant: IOSAdMobControllerGADAddTestDevices_m_1032479912_0) "_GADChangeInterstisialsUnitID", referenced from: IOSAdMobController_GADChangeInterstisialsUnitID_m_1592654805_0 in Bulk_Assembly-CSharp_0.o (maybe you meant: IOSAdMobControllerGADChangeInterstisialsUnitID_m_1592654805_0) "_GADChangeBannersUnitID", referenced from: IOSAdMobController_GADChangeBannersUnitID_m1904975498_0 in Bulk_Assembly-CSharp_0.o (maybe you meant: IOSAdMobControllerGADChangeBannersUnitID_m1904975498_0) "_GADSetPositionXY", referenced from: IOSADBanner_GADSetPositionXY_m_113950081_0 in Bulk_Assembly-CSharp_0.o (maybe you meant: IOSADBannerGADSetPositionXY_m_113950081_0) "_GADSetPosition", referenced from: IOSADBanner_GADSetPosition_m575080953_0 in Bulk_Assembly-CSharp_0.o (maybe you meant: IOSADBanner_GADSetPosition_m575080953_0, IOSADBannerGADSetPositionXY_m_113950081_0 ) "_GADSetGender", referenced from: IOSAdMobController_GADSetGender_m_2132413546_0 in Bulk_Assembly-CSharp_0.o (maybe you meant: IOSAdMobControllerGADSetGender_m_2132413546_0) "_GADCreateBannerAd", referenced from: IOSADBanner_GADCreateBannerAd_m_1635387524_0 in Bulk_Assembly-CSharp_0.o (maybe you meant: IOSADBanner_GADCreateBannerAd_m_1635387524_0, IOSADBannerGADCreateBannerAdPos_m552626299_0 ) "_GADCreateBannerAdPos", referenced from: IOSADBanner_GADCreateBannerAdPos_m552626299_0 in Bulk_Assembly-CSharp_0.o (maybe you meant: IOSADBannerGADCreateBannerAdPos_m552626299_0) "_GADRefresh", referenced from: IOSADBanner_GADRefresh_m1262469966_0 in Bulk_Assembly-CSharp_0.o (maybe you meant: IOSADBannerGADRefresh_m1262469966_0) "_GADAddTestDevice", referenced from: IOSAdMobController_GADAddTestDevice_m_2081727017_0 in Bulk_Assembly-CSharp_0.o (maybe you meant: IOSAdMobController_GADAddTestDevices_m_1032479912_0, IOSAdMobControllerGADAddTestDevice_m_2081727017_0 ) "_GADHideAd", referenced from: IOSADBanner_GADHideAd_m711280150_0 in Bulk_Assembly-CSharp_0.o (maybe you meant: IOSADBannerGADHideAd_m711280150_0) "_initGoogleAd", referenced from: IOSAdMobController_initGoogleAd_m777305546_0 in Bulk_Assembly-CSharp_0.o (maybe you meant: IOSAdMobControllerinitGoogleAd_m777305546_0) "_GADShowAd", referenced from: IOSADBanner_GADShowAd_m1860529617_0 in Bulk_Assembly-CSharp_0.o (maybe you meant: IOSADBannerGADShowAd_m1860529617_0) "_GADTagForChildDirectedTreatment", referenced from: IOSAdMobController_GADTagForChildDirectedTreatment_m_1278709222_0 in Bulk_Assembly-CSharp_0.o (maybe you meant: IOSAdMobControllerGADTagForChildDirectedTreatment_m_1278709222_0) "_GADAddKeyWord", referenced from: IOSAdMobController_GADAddKeyWord_m471052922_0 in Bulk_Assembly-CSharp_0.o (maybe you meant: IOSAdMobController_GADAddKeyWord_m471052922_0) ld: symbol(s) not found for architecture arm64 clang: error: linker command failed with exit code 1 (use -v to see invocation)

Please help~