Apple has unveiled iPhone 11, an update to its XR handset, which now features two cameras on its rear and better low-light photography.
It is also expected to announce updates to its higher-end models shortly at a California event that is currently underway.
Sales of iPhones declined last year at a faster rate than the wider market.
The firm also revealed a new version of its smartwatch, which features an "always on" display for the first time.
The Series 5 Watch adjusts how often it refreshes the screen to as little as one frame per second to promise the same 18-hour battery life as the previous version.
It also introduces a compass and sleep-tracking software as well as the new option of a titanium case.
The company added that it will keep its Series 3 model on the market, which will cost $199 (£161), marking a new entry price point for the wearable.
Apple experienced a bigger drop in demand for new handsets than many of its rivals last year.
But the firm recently reported that its active install base - the number of iPhones in use - was at an "all time high".
"Several forces play here," commented Marta Pinto from market research firm IDC.
"Apple designs devices that last longer than an average Android device, and it's been very good at rolling out new versions of its operating system.
"There's also a very good second-hand trade in iPhones, and the overall smartphone market is slowing down.
"But Apple doesn't mind because its focus is now turning to services, and its wearables are also doing well."
The new iPhone line-up is not expected to feature a 5G model, in part because Intel struggled to develop the required modem.
At a time when consumers are holding onto their handsets for longer before upgrading, that could place a further constraint on sales - especially in countries where 5G networks have already launched, such as the UK.
"Given people's loyalty to iPhone, if they really want 5G they'll probably just wait," said Ben Wood from the consultancy CCS Insight.
"That said, don't be surprised to see rivals, particularly Samsung, positioning 5G devices as 'future-proof' options.
"I'm sure they will be arguing that buying a premium priced 4G smartphone right now would be like buying a TV a few years ago that was not HD-Ready."
Earlier at the event, Tim Cook revealed that its two forthcoming subscription services would each cost $4.99 - or £4.99 in the UK - per month.
Apple Arcade - a video games deal offering exclusive access to games that do not feature in-app fees - will become available on 19 September.
It will be followed by Apple TV+ - a TV show and movie-streaming platform with content not available elsewhere - which will make its first programmes available on 1 November.
The latter will be cheaper than rival services from Disney and Netflix, but appears to promise less material at this stage.
In addition, the company unveiled a new iPad.
The seventh generation model has a 10.2in (25.9cm) screen - making it bigger than before - and will go on sale at the end of the month. It is priced the same as the previous model.
More to follow
How phone cameras evolved:
Kyocera VP-210 VisualPhone (1999)
Although there is some dispute over which mobile first featured a built-in colour camera, many credit this handset as having the honour. It featured a 0.11 megapixel (MP) sensor and could only store 20 selfies, but was able to transmit a jerky video feed in real-time at about two frames per second.
Sharp J-SH04 (2000)
Sharp's first photo-snapping mobile placed its sensor on the rear of its handset to encourage its use as an alternative to standard cameras. Its 0.11MP snaps could then be sent to friends via email.
Sony Ericsson T68i (2002)
The handset's optional CommuniCam MCA-20 accessory snapped on to the bottom of the handset, helping keep down the phone's size when not in use. It was limited to taking VGA (0.3MP) resolution shots, but the images could be texted to others via MMS (Multimedia Messaging Service) if they had compatible phones.
Samsung D500 (2004)
This was one of the first handsets to offer more than one megapixel of image quality. What's more it had a flash. Meanwhile the software made it possible to add graphical frames around photos and turn images sepia or apply a "negative" effect.
Nokia N90 (2005)
Nokia's N90 had a somewhat clunky swivel design, but a two megapixel sensor and a lens developed in collaboration with the famed German optics firm Carl Zeiss pitched it firmly at camera enthusiasts.
Samsung G800 (2007)
The megapixel wars were well under way by the time Samsung unveiled the G800. It took 5MP shots, had a 3x optical zoom and even featured a lens-cover slider, meaning that from the rear it could be easily mistaken for a dedicated camera.
iPhone 4 (2010)
Apple's fourth-generation iPhone is widely credited with helping kickstart the selfie craze, despite being far from the first to have a front camera. But at its launch, Steve Jobs was keener to show off how the feature could be used for Facetime, the firm's video chat app.
LG Optimus 3D (2011)
Smartphones with two rear cameras were still a rarity when LG's Android phone went on sale. It used them to create 3D images that could be viewed without special glasses on its display. But 3D phones proved to be as unpopular as 3D TVs, marking an evolutionary dead end for the industry.
HTC One (2013)
HTC's 2013 flagship sought to shift the battle to low-light photography. To do this it made the pixels larger than normal to gather more light, and dubbed them "ultrapixels". The trade-off was that its photos were limited to 4MP.
Nokia Lumia 1020 (2014)
This Windows Phone featured an industry-leading 41MP sensor attached to an optical image stabilisation system. It allowed users to zoom in and crop without worrying about images becoming blurred, or to combine the data to make 5MP photos with less visual noise than would otherwise be the case.
Lenovo Phab2Pro (2016)
This was the first handset to build in Google's doomed Project Tango depth and motion-sensing cameras. They made augmented reality features possible, such as superimposing graphical images of furniture into views of a room. Tango was short-lived, but AR has lived on by other means.
Samsung Note 8 (2017)
This was one of the first phones to feature "live focus" - a facility that allowed users to adjust background blur in their photos before or after taking them. It achieved this by comparing the view from each of its two rear cameras to create a depth map of the scene.
iPhone X (2017)
Apple's tenth anniversary handset introduced its Face ID camera system, which used tens of thousands of infrared dots to map the user's features. As a consequence, the display had to make space for a "notch", which was widely copied by rivals even if they didn't feature such an elaborate facial recognition system.
Pixel 2 (2017)
Google found a way to let users blur the background of their photos using a single camera in its second-generation Pixel. This made it possible to offer the effect from both its front-facing selfie camera as well as the rear sensor.
Huawei P20 Pro (2018)
The Chinese firm's phone was one of the first to feature three cameras on its back. But the standout feature was its ability to produce quality snaps in near-dark conditions by taking long-exposure snaps and then using machine learning software to keep the details crisp.
Oppo Reno 10x Zoom (2019)
This had two unusual camera features. Firstly, one of the rear cameras has a periscope design that directs light sideways into the device's body, making it possible to let users zoom into a shot more than usual without sacrificing detail. Secondly, the selfie camera pops up from the top, making more space for the display.