Set the size of a QPixmap object

Hey all, I want to use QPixmap class to show a photo on a label object.
So I code:
QPixmap pixmap;
pixmap.load(fileName);
update();
ui->iconLabel->setPixmap(pixmap);
But the picture size is not the same as iconLabel. I want to scale the size of that picture by keeping aspect ratio（Make it the same size as iconLabel）
How to realize that？Thx～

QPixmap::scaled

take a look at the picture viewer example that comes with Qt