Most iOS BLE tutorials teach you to scan, connect, and read a characteristic. Then they stop.

Here's what they don't tell you:

1. Background mode is a different protocol.

Your app won't get the same delegate callbacks in the background. State restoration exists, but the documentation is misleading. You need to handle willRestoreState properly or your connections silently die.

2. The 128-device cache will haunt you.

iOS caches discovered peripherals. If a device changes its services (firmware update, factory reset), your app will read stale data until the user toggles Bluetooth. You have to detect this and handle it gracefully.

3. Write-without-response loses data.

It's faster, but there's no flow control. If you blast packets at a BLE device, the internal buffer overflows and you drop data. You need to check canSendWriteWithoutResponse and implement your own queue.

4. Connection timeouts don't exist.

connect(peripheral) will wait forever. There's no built-in timeout. You need to implement your own timer and cancel the connection attempt manually.

I've been building BLE iOS apps for years and put together free courses and resources to help you skip the pain. The BLE Starter Kit handles all of this out of the box.

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