Errors are brought up when things go wrong in the App. An error could happen on the server level, app level or user level. It’s important to provide appropriate type of error message and instructions to help user recover quickly from the error state.
Banner error message
A banner error message is the least interruptive type of error message. It’s used when the error is not critical to current workflow and user can live with it while still working on other tasks.
Full page error message
A full page error is usually an error from the server. It blocks the user from viewing the previous screen and provides a nicer page transition to take the user out of the current workflow. An example is authentication error which the app intentionally blocks user from viewing content from the app but also has abundant space to explain the error and provide solution.
An inline validation message is used only in a form sheet. It’s displayed directly with the input cell and explains the error with suggestions to correct the error.
Standard iOS alert can be used for App or Server error. Limit the usage of standard iOS alert and use it only for serious issuesA standard alert. For additional information about standard iOS alert, visit iOS human interface guideline.