Can I use the Ext JS GPL?
GPL is opensource. You will have to share all your source code public and with Sencha.
- You can't use GPL for commercial software.
- You can't build your project with GPL and later change the license, the project needs to be created with the correct license from the start.
- Sencha Architect won't work with GPL
Also, according to Apple AppStore rules, you are not allowed to add GPL projects to their stores.