Fix removePeripheralsFromCache to iterate the right things. (#26670)

We're using the things we get out of the iterator as keys into the cache; these
are not the values.
diff --git a/src/platform/Darwin/BleConnectionDelegateImpl.mm b/src/platform/Darwin/BleConnectionDelegateImpl.mm
index ad10930..39ca6f5 100644
--- a/src/platform/Darwin/BleConnectionDelegateImpl.mm
+++ b/src/platform/Darwin/BleConnectionDelegateImpl.mm
@@ -698,7 +698,7 @@
 
 - (void)removePeripheralsFromCache
 {
-    for (CBPeripheral * peripheral in [_cachedPeripherals allValues]) {
+    for (CBPeripheral * peripheral in [_cachedPeripherals allKeys]) {
         [self removePeripheralFromCache:peripheral];
     }
 }