ios - warning: Could not resolve external type c:objc(cs)NSObject

更换了友盟分享的第三方库之后，就开始报这个警告
warning: Could not resolve external type c:objc(cs)NSObject
while processing /Users/whqfor/ios/Pods/UMengSocial/Umeng_SDK_Social_iOS_ARM64_4.3/UMSocial_Sdk_Extra_Frameworks/SinaSSO/libWeiboSDK.a(WBSDKNormalWebViewController.o):
warning: Could not resolve external type c:objc(cs)NSDictionary
while processing /Users/whqfor/ios/Pods/UMengSocial/Umeng_SDK_Social_iOS_ARM64_4.3/UMSocial_Sdk_Extra_Frameworks/SinaSSO/libWeiboSDK.a(WBSDKNormalWebViewController.o):
warning: Could not resolve external type c:objc(cs)NSString
while processing /Users/whqfor/ios/Pods/UMengSocial/Umeng_SDK_Social_iOS_ARM64_4.3/UMSocial_Sdk_Extra_Frameworks/SinaSSO/libWeiboSDK.a(WBSDKNormalWebViewController.o):
warning: Could not resolve external type c:objc(cs)NSObject

找了一些解决方法，其中一个是：
I had this problem too. Here's how I fixed it.
1) Go to Build Settings -> Build Options -> Debug Information Format
2) Change the Debug setting from "DWARF with dSYM File" to "DWARF"
3) Leave the Release setting at "DWARF with dSYM File"
The problem appears to be that Xcode was trying to create dSYM files for Debug builds. You don't need dSYM files for Debug builds -- it's release builds where you need them.
但是这样在release模式下，还是有警告，并且不知道这样设置的作用是什么。