I want to read the UID from the tags that I have but i Don't know what to do. I'm using a NTAG125 tags

Hi everybody. I have a question about NDEF Messages. I just begin to learn CoreNFC from tutorials and Apple documentation. I'm trying to do an app with a Form and I want to write those TextFields into a NFC Tag . The tag that I'm using is a NTAG 125 wich works perfectly with IOS, but this is my problems I don't understand very well how payload works. Is possible to write a dictionary in the Tag ? or I'm forced to write each record at the time? For example: I want to write this in my Tag username: "Rafael" lastname : "Castro" Id: 0701334445 loginDate: 2021-11-02 Since I may be updating the Tag from time to time if instead of one register, the ones wrote down in my tag are 4 I thing I will be depleting the tag memory very quickly. Someone can help me with this ? Thanks in advance !

Hi guys, my question is this: How I can make a private app only for me ? What I need to do for this? I'm new in developing apps for IOS and I want to test and app that I´m making for my Master Thesis which uses NFC technology. That`s why i need t use my physical device because I´m using it as a reader. My apps needs to comunitcate with a web server that I own. What are the procedures that I must follow to be able to test my app in my own apple phone ? The only one that need access to the app is me. I don´t understan very well if I can do this for academics purpose or I need to be member of one of the other developers plans that are available and in this case which one is good for me ? Thanks in advance for your answers !