Can they read text messages on an iPhone?
Eye in the Sky
You should assume that messages can be read. I have heard of court cases where they subpoenaed surveillance footage where they zoomed in on someone's phone and could read the message. I have also talked with surveillance operators who say this is doable. A casino with older equipment might have a tougher time doing this, but as a general rule, if it's something you wouldn't want read my surveillance, it shouldn't be looked at on the casino floor.