There’s a whole lot covered on this list, and some of the tricks will undoubtedly be things you’re already familiar with. But the tips are varied enough that everyone is bound to learn at least something
Here are a few examples of nifty iPhone tips in this thread:
Swipe left "Low Power Mode disabled" notification to enable it again.
3) Swipe up on two or even three apps at a time with multiple fingers in task switcher to close all quickly.
4) Hold the '.com' button while typing URL, its gives other domains like .net or .org, so you don't have to type it.
5) Tapping "123" then tapping the character you want then finally clicking back to the main keyboard can be a hassle. Instead hold down "123", slide thumb to character you want to use then let go. The character will be inputted and your keyboard will be back to normal.
6) Shake your iphone to Undo.
7) Tapping the clock/top bar on a page will take you quickly to the top.
8) Tap chunk of text with 2 fingers to highlight the whole thing. Works only when commenting/editing etc.
9) Be careful, actually there is no proofed solution to turn this off again! If you go into the phone app, and dial 3001#12345# (add * before and after the number) and hit call, the "Field Test" application opens, which allows you to see the numerical value of your cellular reception, along with other information about the surrounding cell towers. In addition, if you hold down the power button until the "Slide to power down" slider comes up and then hold down the home button until the app exits, you can tap on the carrier name in the top left corner to change between the numerical value and the visual representation (in bars) without going into "Field Test" mode. The values are always negative. In my experience, around -50 is pretty much the best reception possible, while about -120 is the lowest you can go without losing reception. Anything above -80 is good, and would be considered full bars Anything below -100 is bad, and would be considered few bars
10) Double click the upper case arrow to set caps lock
11) Force close a single app by holding the power button until the slide to power off slider appears, then press and hold the home screen button. It will close any app that you are in and also remove it from the RAM, forcing it to completely reload upon re-opening. Fixes many problems.
12) This may have been obvious but you can zoom in and out in the default Camera app by using two fingers to pinch and spread.
13) You can use more than a 4 digit PIN number. By turning off "Simple Password" and choosing only numbers instead and NO letters. You will get a number keypad to unlock the phone instead of a full keyboard. And you can use as many numbers as you would like and you you have to press OK to enter it. This makes your PIN number much much harder to guess. Since you would need to not only guess the number but also how many digits the pin contains to break in.
14) Swipe away banner notifications that inhibit you pressing a button on the top of the screen by swiping from RIGHT TO LEFT (will not work L TO R).
15) In Mail, holding the "New Email" button will display all your recent drafts.
16) Tapping the screen with two fingers while in Maps will zoom out
17) Add a shortcut for your email address (example @@). It makes filling in online forms much, much easier. Settings > general > keyboard > shortcuts
18) Put a tracking number for UPS or some other mail services in a text field (notes, e-mail, text) and it becomes a link to the tracking website.
19) To continue listening to a video or music video from safari after exiting safari, just double click the home button, go to music controls, and press play. Also works on the lock screen, useful for music videos, etc.
20) Sleep Timer - While playing music in the Music App , toggle to the clock app click timer, click "when timer ends", scroll to bottom, click stop playing. Start Timer.
21) Pressing the volume buttons when alarm clock goes off for the snooze. I've caught myself accidentally turning it off instead of pressing the snooze button and find this method much safer and easier.
22) If you turn on accessibility settings you can tap out a custom vibration pattern or make the bright camera LED flash when you get a call or text. Then go into contacts, hit Edit and you can select the vibration below the ring tone. From iOS 6, the custom vibration settings have moved to Settings > Sounds. You click on each individual alert type and you have to option to set a custom vibration.
23) If you're getting a call you can just press the lock button to mute it instead of pressing decline. Pretty useful for when your phone starts blasting in your pocket during a class or meeting! Works also with the volume keys.
24) Holding the keyboard globe icon gives you a list of keyboards that are on. Swipe from leftmost of screen to right in camera to access the camera roll instead of clicking it from the bottom.
25) In camera app, use the volume buttons as a picture clicker.
26) To reset the new message counter. Lets say you have a bunch of unread emails and you don't want to click through all of them. Click edit, select the first message, hold down the Mark button and click the same message to unselect it. Voila! All the messages are selected! Click Mark as unread.
27) When websites have embedded content that scrolls (like an extra area with scrollbars), you can use 2 fingers to navigate through it. This works with textareas for example.
28) You don't have to swipe the homescreen to go to the next, you can simply tap the left corner/right corner right above the first and forth icons on the dashboard.
29) Here's for the lazy ones: end a phone conversation by pressing the lock button. This way, you can terminate the call and locking the screen in one press.
30) If you want to search for a word on a page with safari, enter it in the web search box on the top right and scroll all the way down, past the suggestions until it says 'on this page'.
31) You can use rich text styling in the mail app. Select some text and bring up the context menu, then press the arrow right. You can use bold, italics, underline, and indenting.
32) *#06# displays your iPhone's IMEI. Good to take down if you don't have the original box around you. You'll need the IMEI if your phone gets stolen or dislocated, in order to file a report with the police and/or a claim with the insurance company.