Everyone loves a top 10 don't they? Well this one from Ole Begemann is a good set of tips to make working AutoLayout more bearable.
If a top 10 wasn't enough, how about a top 25? Marcelo Fabri has written up a set of tips for increasing your app performance. Split into beginner, intermediate and advanced sections this is a solid set of recommendations if you are struggling with performance.
Jay Graves with an explanation of SSL pinning and then a guide to implementation. If you need to be sure that you are talking to the right server rather than a man in the middle before transferring data then you will want to take a look at this.
Core Graphics blending modes can be a little confusing if you are coming at them for the first time. If you are in this camp then Gordon Fontenot has an article taking you through the basics of blending drawing code with grayscale images to produce tinted images.