fix bug

metal/paddle-mobile/paddle-mobile/Net.swift

@@ -24,7 +24,7 @@ public class ResultHolder: NSObject {
     capacity = inCapacity
   }
   
-  public func releasePointer() {
+  @objc public func releasePointer() {
     result?.deinitialize(count: capacity)
     result?.deallocate()
   }

metal/paddle-mobile/paddle-mobile/PaddleMobileGPU.m

@@ -49,6 +49,7 @@
       [resultArray addObject:[NSNumber numberWithFloat:result.result[i]]];
     }
     completion(success, resultArray);
+    [result releasePointer];
     
   }];
 //  [runner predictWithTexture:texture completion:completion];