The real limits for the alert text are not documented anywhere.
The only thing the documentation says is:
In iOS 8 and later, the maximum size allowed for a notification payload is 2 kilobytes; Apple Push Notification Service refuses any notification that exceeds this limit. (Prior to iOS 8 and in OS X, the maximum payload size is 256 bytes.)
This is what I could find doing some experiments.
- Alerts: Prior to iOS 7, the alerts display limit was 107 characters. Bigger messages were truncated and you would get a "..." at the end of the displayed message. With iOS 7 the limit seems to be increased to 235 characters. If you go over 8 lines your message will also get truncated.
- Banners: Banners get truncated around 62 characters or 2 lines.
- Notification Center: The messages in the notification center get truncated around 110 characters or 4 lines.
- Lock Screen: Same as a notification center.
Just as a reminder here is a very good note from the official documentation:
If necessary, iOS truncates your message so that it fits well in each notification delivery style; for best results, you shouldn’t truncate your message.
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