`iframe id=pngNewCase1143241142570_IFrame`., this id changes dynamically every time how can i handle this in **selenium webdriver java**
I tried using 

```
driver.switchTo().frame(driver.findElement(By.xpath("Xpath of Iframe which changes dynamically")));
driver.switchTo().defaultContent();

```

but didn't work for me

also tried 

```
driver.switchTo().frame(driver.findElement(By.Id("pngNewCase1143241142570_IFrame")));
driver.switchTo().defaultContent();

```

can anyone help me please