fixed possible accuracy losing of NSDecimalNumber

YYModel/NSObject+YYModel.m

@@ -572,11 +572,18 @@ static force_inline void ModelSetNumberToProperty(__unsafe_unretained id model,
             ((void (*)(id, SEL, uint32_t))(void *) objc_msgSend)((id)model, meta->_setter, (uint32_t)num.unsignedIntValue);
         } break;
         case YYEncodingTypeInt64: {
-            ((void (*)(id, SEL, int64_t))(void *) objc_msgSend)((id)model, meta->_setter, (int64_t)num.stringValue.longLongValue);
-            break;
-        }
+            if ([num isKindOfClass:[NSDecimalNumber class]]) {
+                ((void (*)(id, SEL, int64_t))(void *) objc_msgSend)((id)model, meta->_setter, (int64_t)num.stringValue.longLongValue);
+            } else {
+                ((void (*)(id, SEL, uint64_t))(void *) objc_msgSend)((id)model, meta->_setter, (uint64_t)num.longLongValue);
+            }
+        } break;
         case YYEncodingTypeUInt64: {
-            ((void (*)(id, SEL, uint64_t))(void *) objc_msgSend)((id)model, meta->_setter, (uint64_t)num.unsignedLongLongValue);
+            if ([num isKindOfClass:[NSDecimalNumber class]]) {
+                ((void (*)(id, SEL, int64_t))(void *) objc_msgSend)((id)model, meta->_setter, (int64_t)num.stringValue.longLongValue);
+            } else {
+                ((void (*)(id, SEL, uint64_t))(void *) objc_msgSend)((id)model, meta->_setter, (uint64_t)num.unsignedLongLongValue);
+            }
         } break;
         case YYEncodingTypeFloat: {
             float f = num.floatValue;