The iPhone is highly customizable, allowing users to change everything from wallpapers, to the arrangement of icons, to parental controls. One way to customize your iPhone is to increase the length of time your wallpaper screen stays on. Lengthening the time that the screen stays on also extends the time before the phone becomes locked.
Click on the "Settings" icon on your iPhone.
Scroll down to General Settings and select the "Auto-Lock" feature. Here you'll have the ability to customize the length of time that your wallpaper stays on before the phone goes black and becomes locked.
Choose an amount of time that you want to keep your iPhone wallpaper screen on by clicking on a time between one and five minutes. You can also choose "Never," which will prevent your iPhone from ever Auto-Locking. If you are considering selecting the "Never" option, it is important to remember that keeping your phone unlocked, and constantly displaying your iPhone wallpaper screen, will drain your phone's battery faster.