Common iOS development mistakes

• Only setting values one-way in cells

if (something)
{
    cell.textLabel.font = [UIFont boldSystemFontOfSize:14.0f];
}
// Missing the else case - if the cell gets reused, the font doesn't get reset

• Input view and input accessory view not used
• Animating frame of table/scroll view instead of content inset
• Networking in the controller