重写referrerId的get方法，会自动获取

Pod/Classes/UIResponder+PhobosPV.h

@@ -9,5 +9,9 @@
 #import <UIKit/UIKit.h>
 #import "PhobosPVProtocol.h"
 @interface UIResponder (PhobosPV) <PhobosPVProtocol>
+
+/**
+ 只适用于controller自动初始化referer
+ */
 - (void)initReferer;
 @end

Pod/Classes/UIResponder+PhobosPV.m

@@ -78,7 +78,21 @@
 
 - (NSString *)referrerId {
     NSString *referrerId = objc_getAssociatedObject(self, @selector(referrerId));
-    return referrerId == nil ? @"" : referrerId;
+    if (referrerId == nil) {
+        if ([self isKindOfClass:[UIViewController class]]) {
+            NSArray *navigationPool = ((UIViewController *)self).navigationController.viewControllers;
+            NSInteger refererIdIndex = navigationPool.count - 2;
+            if (refererIdIndex < 0) {
+                return @"";
+            } else {
+                UIViewController *controller = navigationPool[refererIdIndex];
+                NSString *preBusinessId = controller.businessId;
+                objc_setAssociatedObject(self, @selector(referrerId), preBusinessId, OBJC_ASSOCIATION_COPY);
+                return preBusinessId;
+            }
+        }
+    }
+    return referrerId;
 }
 
 - (BOOL)needLogPV {