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Saved by @CodyyyGardner

It makes me smile every time I notice IGListKit at work in Instagram. We put a lot of work into making and improving it. Proud to see it holding up 4 years later.

🧵 with some memories on how it was built:

 At Instagram, product work slowed around the holidays, so we used the time to pay down tech debt. In winter 2014 I reviewed a +12k line refactor from UITableView to UICollectionView.

We recently dropped iOS 5 so we could use the new 6+ APIs without backwards compatibility.
That review taught me a lot about UICV: data sources should mutate in one place else risk out-of-sync exceptions, the first view layout may reloadData, sticky headers make good perf hard, and many more UICV tidbits
We used reloadData for everything and it worked, for the most part.

Except two things bugged the hell out of me:

1. No animated changes (duh)
2. Images could flicker and the like animation could cancel
I dug into the latter and learned that if you reloadData, every cell on screen gets reused. So even if nothing in the UI changes, you still reuse (or init) cells, bind data, set images, etc. that’s a lot of work!
When you liked a post, we’d call reloadData. Since all cells are replaced: we had to track the liked row, reload, and THEN perform the like animation. 😓

If something triggered another reload after the animation started, the cell cancelled the animation (thus the UI bug)
The image flickering issue was simpler:

When an image cell is reused set the background to grey, async load the image (cache or network), set the image. The async time between reuse and fetch/set from cache is where the flicker came from.
(@ryanolsonk solved the image flicker with an insanely clever “weak image cache” design. It’s a great interview question 😉 )
This all got me thinking: what if we only updated cells when the data changes? This general idea was gaining traction (ahem, React): bind data to views, and diff the data on change to only rebind changed data+views.

Enter UICV performBatchUpdates
Using the principle of only updating the data source in one place, I could diff the from/to data and use UICVs APIs to insert/delete/reload/move. Anything unchanged wouldn’t get touched!

So how the hell do I write a diffing algorithm? I literally had never done this.
I researched several algos: rsync, Myers, react...

I settled on Paul Heckel’s https://t.co/jpxuHNlpXg

Why?

1. It’s output matched UICV’s APIs: inserts, deletes, updates, and moves
2. There were example implementations I could actually understand
A pivotal decision was how we define identity and equality. I wanted to piggy-back off NSObject’s -hash and -isEqual: methods to spare our engineers having to write/understand diffing concepts.
@ryanolsonk convinced me I was wrong bc writing proper -hash is complex https://t.co/4PgDCykAna

Foundation hashes can collide
https://t.co/h9eVHO342U

Or are too basic for diffing
https://t.co/Pp0eVFRS5e https://t.co/ZNPJnXlXa4
We settled on a hybrid API: a protocol with custom identifier and -isEqual: We later scrapped the NSObject tricks as they were easy to abuse & forget, resulting in crashes.
Fun fact: the library was originally called “IGStoryKit” but my director hated that so we renamed it. Glad we did, guess what launched 6 months later? 🤪
Over the next several months, @jesse_squires and I refactored probably 20k lines so that we could run our new infra alongside the old one. This let us safely A/B test performance before rolling out.
We started with single-item feeds but quickly moved to support the main feed. Main feed was scary (we were starting to run ads 😬) but if we could replace feed, then the rest of the app would fall in line.
@ocrickard and I spent a couple months investigating crashes and tuning performance. I learned a lot about ObjC++ during this time (unordered_map was waaaay faster than NSDictionary for our diffing).
We ended up filing 4 UICV radars from all this investigation! Some have been closed

https://t.co/BACvyI2l08+
When everything was fixed, we launched. I spent a year advocating the eng org help refactor and deprecate the old infra. It came down to the profile view. I rolled up my sleeves and did it myself. It was TOUGH

With profile done, I submitted a -12k change to remove the old infra.
From the start we wanted to open source the library. It ended up being a lot of paper work and internal politics, but we did it. Forever grateful to @jesse_squires for setting the project up for success and @mikeyk for having our back.
We started writing the library in late 2015, launched feed summer of 2016, and deleted the old infra in early 2017.

Throughout this the eng team 10x’d and users 4x’d, we launched tons of products (Stories!), IG opened a NY office, UICV got diffable data sources, and more.
After we launched 4y ago I calc’d our diffing algorithm executes over 40,000 times a second. I can’t imagine what that is now!
Building IGListKit was a career’s-worth of learning packed into a couple years.

I’m proud that it’s still powering Instagram today, but I’m looking forward to learning about what replaces it.

More from Social media

Rudy Havenstein, Check out the fact-checkers.
Rudy Havenstein, Check...
@RudyHavenstein
So let's check in on "Newsguard," one of the Orwellian groups (e.g., The Atlantic Council) that totally reliable sites like @voxdotcom and @axios use to decide what is "Unreliable" and "fight disinformation."

One example:

OK, so "The Daily Wire" and "https://t.co/oEa89coNak" are unreliable. Fair enough, maybe they are (I don't use either one of them).

So let's look into one of our new official arbiters of "reliability," Newsguard!

What's their advisory board look like?

https://t.co/5N8op70VE1


OK, so maybe a few names jumped out at you immediately, like, oh I don't know, (Ret.) General Michael Hayden, former Director of the CIA AND former Director of the National Security Agency in the run-up to the Iraq War in 2003! Google him, he's famous!


Newsguard is all about "seeing who's behind each site," (like how Michael Hayden is behind Newsguard?)

All they want to do is fight "misinformation." That's laudable, right?

Also, Newsguard has a "24/7 rapid response SWAT TEAM!!"

So cool!
https://t.co/EDN3UXvBR9


Ok, I'm not a journalist or a former CIA director, so I have no idea what's true or not unless someone tells me, so hey, Columbia Journalism Review - what do you think of Newsguard Advisory Board Member Michael Hayden?
SOCIAL MEDIA
Sunshiny
Sunshiny
@sunnshiiny
As we wait for the transition of power from despot to democrat, Facebook (Zuckerberg) has taken it upon itself to aid in the obstruction of that power transfer, facilitation of an insurrection narrative and disregard for the will of the American electorate.


In other words, the Social Media monopoly Facebook commands globally has gone full fascist in an attempt to preserve the corrupt and criminal hold on power by Republicans and Trump Administration.

Aiding and abetting a coup d’état.

As if there weren’t enough other reasons to dismantle Facebook’s monopoly, Zuckerberg is playing his cards and revealing clearly that Cambridge Analytica election interference was not just a onetime anomaly, but is now a feature of Facebook’s business model.

Megalomaniac Marc has now revealed the true colours of Fascist Facebook.

Facebook is a weapon to manipulate the masses. A tool to carry out disinformation campaigns with impunity.

And the response of the left... is to delete their Facebook account.

As if the deletion of a Facebook account will do anything. It might send a message that your virtues are principled, your morality superior. But it enables the weapon to be continued to gaslight and manipulate the electorate.

An inherent flaw in the left’s critical thinking.
SOCIAL MEDIA
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Ranveer Allahbadia
Ranveer Allahbadia
@BeerBicepsGuy
How I built a 7 Million+ strong COMMUNITY on social media, in 5 years.

(A thread)

Video content is the past, present & future.

Golden rule of social media : People gravitate towards HUMANS & their stories.

The easiest way to attach people to your journey is COMMUNICATION through video.

If you cant come on screen, at least use voice. Video>Photo>Written.


From day 1 :
- Wrote down ALL ideas on paper (content pieces, growth strategies, future targets)
- Decided to expand my team, whenever my income allowed me to.
- Make. Money. First.
Don't just rely on YouTube income or brands for money. You may also provide SERVICES to fans.


But in the long term, BIG money will come from brands.

Therefore accumulate numbers and create your own niche.

How to get numbers?
- Entertain or Educate or Motivate

- Create videos/pieces that address people's most common questions/thoughts about the niche you've chosen.

As you grow through your base strategy of video creation (could be YT, IG Reels or even LinkedIn Video)...

You can further community loyalty through sharing pieces of your personal story. How?
- Vlogs
- Captions that expose your mindset.
- Tweets

Be a good storyteller.
SOCIAL MEDIA
Sall Grover
Sall Grover
@salltweets
1. I'm the CEO of a platform for females & know I have a unique insight into the single sex space debate. I see it play out in real time.

During our 1st MVP test phase, 1000s of TW onboarded & created "KILL TERF" profiles.

Are we supposed to take these seriously or not?


2. I fought to include TW on Giggle but the reality is I fought not knowing the hostility of the situation. I was shocked & devastated by the KILL TERF & other obscene profiles, but...

Is "KILL TERFS", "RAPE TERFS" & "LOOK AT MY GIRL DICK" what we can except in the real world?

3. Is it "just" something said to women online or is it something that would be done in "analogue" female spaces?

It's a really important questions to ask, because not only do women not want to read stuff like this... we don't want to physically experience it either.


4. It's important to remember, without this abhorrent behavior we'd all be having a very different debate.

This behavior has *added* to womens fear.

You can dismiss it if it doesn't suit your agenda. But if you do, no solution to ensure the safety of *everyone* will be found.

5. When I read something like this, what stands out to me is the line "a lot of the time I'll get side eye or even outright harassment." Lucky you!

Imagine getting a rape threat.

When that statement is put into the context of the admission prior to it, it's scary for women.
SOCIAL MEDIA
Venkatesh Rao
Venkatesh Rao
@vgr
social media use really calls for something closer to a driver's license than terms of service... most apparent bad behavior here is more incompetence than malice, like not knowing how to change lanes or take turns at a 4-way stop..

trump's history on twitter is something closer to a crazy car chase on LA streets than bad driving (with the cops MIA, but media helicopters in pursuit), but almost all unpleasantness around here is just poor driving skills

not that I'm advocating for a licensing regime... that would be a terrible thing. Do not need a social media DMV. But the underlying principles (as tested for eg. in the written and road tests) are pretty good.

Written test would test things like "safe following distance" (reply-guying = tailgating?)

Road test would actually expose you to routine provocations. Like, "make a left turn" = "deal with this concern troll"

As in the driving test, where an awkward, unnatural, and unintuitive bit, the parallel parking test, is the toughest bit, there would be some such awkward maneuver you'd have to learn (hmmm... what's the parallel parking equivalent on twitter?)
SOCIAL MEDIA

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Invest Like the Best
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In 1937, a trucker got frustrated waiting for his cargo to be unloaded. He later sold his company for $1.1 billion.

Here’s the story of how Malcom McLean made a billion dollars and which startup could be following in his footsteps. (Inspired by our episode with @laurabehrenswu)


In the early 1950s, the shipping industry was a dying business.

New York’s docks were handling half as much domestic cargo in the early 1950s as they had been in the depressed 1930s.

In thirty years, no one had invested significant money in coastal shipping.

Why?

As McLean found out, loading ships was difficult and slow.

A truck or train would deliver items to the port. Each item was unloaded separately, recorded, and carried to storage.

When a ship was ready, each item was taken from storage, counted again, and hauled on-board.


The cost of this labor was significant. As one expert at the time explained:

“A four-thousand-mile voyage for a shipment might consume 50 percent of its costs in covering just the two ten-mile movements through two ports.”


Yet, despite the industry’s issues, it felt little pressure to change.

Foreigners were barred from operating domestically. Cartels ran international routes. And gov. subsidies eased the pain of labor costs.

Reshaping the industry needed an outsider.

Enter Malcolm McLean.
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Sharing one incident... After Modi's Trichy youth conference, the very next morning when police were clearing up their mini-control room, they found 5 strange boys who were roaming there with bags. When police enquired them "Sir, we are from Subramaniapuram in Trichy.

Whatever political meeting or conference is held in this ground, we come here on the same night or morning hours to collect the Liquor bottles to sell in the scrap shop for 50 paisa to 1 rupee per bottle and we used to earn Rs 200 to Rs 400 on each such event.

Even in the last DMK meeting the very next day we collected around 1500 bottles. But for Modi's BJP meeting, we could not find even a single bottle in the whole ground. We are coming around and around and not a single bottle in any corner of the G Corner ground in Trichy,

we are much disappointed, sir!". Police seem were stunned and pleasantly surprised. This is what Modi magic does in this nation. Modi is the one who can lead our nation and make everyone prosper with hardwork in right direction and proper approach.

This funny but interesting anecdote was published by a statewide local daily Dinamalar. I have just translated and posting it here for rest of the nation;
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Sumit Grrg
@sumitgrrg
These 10 threads will teach you more than reading 100 books

Five billionaires share their top lessons on startups, life and entrepreneurship (1/10)


10 competitive advantages that will trump talent (2/10)


Some harsh truths you probably don’t want to hear (3/10)


10 significant lies you’re told about the world (4/10)
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SRISAILAM: KASHI OF THE SOUTH (AP)
#andhratemples

The divine abode of Mallikarjuna Swamy (Jyotirlinga) and Devi Brahmaramba (Shaktipeeth).

When Ganesha was married before Kartikeya, he left in anger to Kraunch mountain. Shiva and Parvati also followed him there.


Shiva assumed the form of Jyotirlinga and resided on the mountain by the name of Mallikarjuna. Mallika means Parvati while Arjuna is another name of Shiva
It is also said that once, a princess Chandravathi, saw a cow shedding milk on a rock resembling a shivlingam.
@DubeyYash1911


She started praying to the lingam daily and used to offer jasmine (mallika pushpam) daily. Pleased Shiva appeared before her and agreed to wear jasmine garland (mallika pushpmala) on his head permanently. Since then, Shiva became known as Mallikarjun Swamy.


At this place, Shakti took the form of Bhramaram (bee) to kill Arunasur and settled as Bhramaramba Devi. The place is a Shakti Peeth as the neck portion of Devi Sati fell here.

It is said that by merely seeing the hill, one is emancipated from all his sins and worries.
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Professor
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So friends here is the thread on the recommended pathway for new entrants in the stock market.

Here I will share what I believe are essentials for anybody who is interested in stock markets and the resources to learn them, its from my experience and by no means exhaustive..

First the very basic : The Dow theory, Everybody must have basic understanding of it and must learn to observe High Highs, Higher Lows, Lower Highs and Lowers lows on charts and their

Even those who are more inclined towards fundamental side can also benefit from Dow theory, as it can hint start & end of Bull/Bear runs thereby indication entry and exits.


Next basic is Wyckoff's Theory. It tells how accumulation and distribution happens with regularity and how the market actually

Dow theory is old but
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