For Android it is difficult to give general instructions since every model differs. You can switch between the keyboard easily after it is installed through the world icon, that will be shown on the keyboard. For iPhone, this is in Settings -> General -> Keyboard.
KEYBOARD SHORTCUT FOR A WITH UMLAUT INSTALL
You can install a German keyboard in the settings of your phone. On your iPhone or Android: For the advanced daily German writer On most phones you will have a pop-up with special letters appear if you long-press the letter on the keyboard. On your iPhone or Android: For the casual German learner For ß you need to press CTRL + ALT + S together. Once you have set-up the keyboard just type ” + the corresponding vowel = ä ö ü. You can set-up either the US International Keyboard or the German keyboard.
On a PC: For the advanced daily German writer
Hold down the “alt” key on your keyboard and type one of these codes: If you are already familiar with using alt codes, simply select the alt code category you need from the table below. Select the Option ” Show Input menu in the menu bar” to be able to switch between your German and English keyboard easily Welcome to Useful Shortcuts, THE Alt Code resource.If you are typing German more often, why not install the German keyboard? You will need to remember where to find each key, but if you type German often this is the best way. On a Mac: For the advanced daily German writer Then just press the number corresponding to the letter. If you are on a Mac, you only need to press the corresponding letter down and keep holding it. On a Mac: For the casual German learner Umlaut Menu Mac ß (scharfes S) is technically not an Umlaut, but is included here for completeness. To write German on a PC or a phone correctly you will make use of Umlauts (the letters with the dots above them).