May 25, 2011
Jamar Parris asks:
I’ve really been contemplating whether to focus my efforts on one versus the other as I’m still new to both technologies. What impact do you think will HTML5, CSS3, WebGL, etc have on Objective-C iOS developers?
The question web versus native is one that makes waves every once in a while when there is support for a new formerly native technology in browsers or when Apple rejects an app. Let me expand my answer a bit, as there were a couple of recent experiences that serve well to underline my opinion on this question.
May 18, 2011
Daniel Wood asked:
Considering making a Blockees universal. What are people’s thoughts on universal apps? Good for users, but splits sales between devices.
My first gut response was, that IMHO users love universal apps, whereas marketeers and financiers hate them. HD or “for iPad” versions can generally be sold for a higher price.
Daniel then voiced his fear that if you have an universal app you might “dilute” your download rank on iTunes. Again I responded from my feeling that I don’t think that this is right. Daniel challenged me to prove it. And so I will.
Mar 10, 2011
Peter Reinhardt asks:
The app AppSwitch displays the console entries from NSLog logging in the iphone app. I tried to figure out how they do it but couldnt find an API. Do you have an idea?
Intriguing question! My first gut reaction was that the guys from AppSwitch must have some magic sauce as I didn’t know of a way to access the console log on device like the Xcode organizer is able to. My first response was that probably they are doing some stderr bending as is possible with c++. But then I bought the app to see their trick with my own eyes.
In this blog post I’ll show you how that’s done.
Mar 09, 2011
Communicating with web services you have to decide on a way to transport the date back and forth. Recently – with the help of the popular Twitter-API – JSON seems to have come ahead in the race. Other contenders are property lists and XML. Property Lists (PLISTs) are available in XML-Text and a binary (“old”) format and are widely supported in the Apple APIs which makes them a joy to work with.
JSON files on the other hand are easy to be generated server-side as they are basically just concatenated text, much less verbose than pure XML. The binary alternative might also be a contender when it comes to performance in transmission and parsing, provided some component is installed on the server to generate them.
In this blog article we are trying to answer the question once and for all what you should use in your own apps.
Dec 23, 2010
Elias Sanchez asks:
Hello Oliver. Quick? Do you have any tips in making a toolbar appear/disappear? Trying to mimic what the NYT app does when looking at an article. Is it using Core Animation perhaps? Can’t find anything out there. Any ideas? ThxU
Looking at the NYT App you can see that they do quite a bit of manipulation of the bars of which there are 3: Tab Bar, Navigation Bar and sometimes a Tool Bar.
For beginning iOS Developers it might seem daunting to combine all of these for the effect that the NYT App achieves. In this article I give you an analysis of what they did so that you have their techniques at your disposal, too.
Jul 16, 2010
I’m interested in getting your questions because answering them helps me structure the material in my head. And there’s a saying that “what you teach you learn”, because of that.
Devin Snipes, an aspiring young iOS Developer asks:
Hello Dr. Touch,
My name is Devin Snipes, I’m 15 years old and I’m an iPhone Developer. I’ve been following your work for a little less than a year, and I’ve grown to love it. Your work is amazing, and I hope to someday be as good as you are in programming for the iOS platform. I currently have a few iPhone applications on the AppStore, but nothing compared to yours.
I’d like to ask you a few questions that will hopefully give me more insight on your developmental skills and how I can improve on my skill.
Well, “You catch more flies with honey than vinegar”. If somebody asks so nicely I’ll usually try to respond with something useful.
1. How did you become so great at programming for the iPhone?
I’m doing it full time only since last December. And before that I was looking at code on most days for a couple of hours. Do you know the rule of 10,000? It says that if you want to be world-class in any field you have to invest 10,000 hours in total. Before I got into developing for the iPhone I was collecting programming time for many years. So I probably reached 10,000 a while ago. But that’s not strictly Cocoa time. At 10 hours a day it takes you around 3 years to reach 10,000. So I’m probably around 5,000 hours doing iPhone stuff.
Jul 01, 2010
Thanks for your article on UIImage from UIView.
Need one more favor; I am in situation where I want to draw line or area (e.g. rectangle) on UI Image (e.g. Blue print) and save it again.
Basically I will show image and put circle / rectangle on image showing area in blue print and save it.
How should I do that? Can you please suggest approach, sample codes etc?
So the task is to take a UIImage, make it writable in some way and then make a new image out of that for later use. Off the top of my head, I can immediately think of two ways to do that: with UIKit and with CoreGraphics. CoreGraphics has a slight advantage, being lower level, of being thread-safe. But for a simple graphical addition to an existing image I see nothing wrong with UIKit. As usual you should only do very quick operations with UIKit because it requires to be run on the main thread which is the only thread updating the user interface.
Jun 22, 2010
A not-to-be-named friend asked me:
I would like your opinion the GM build. Should I (not sure how) remove it and then load the new iOS 4.0? I know it wouldn’t have the game center, but I don’t use that anyway. I am afraid if I don’t remove, the software will expire (happened on beta 4 and then I couldn’t use the phone (or back up first) until I could load the latest.
If you’re one of those developers that managed to install the iOS 4.0 Gold Master right after Uncle Steve announced it, then you might wonder if you should update to the really final release that came out just now.
Wait! That’s a trick question…!
Mar 18, 2010
Hey guys just wondering how to put a timer in the appdelegate. I need a timer to keep playing on through multiple views instead of just playing on 1 view. Any help apperciated
Using timers is pretty simple. There are plenty examples around and it’s not difficult to understand. Having said that, I am responding to this question for three reasons:
- my posts on my blog have been pretty scarce recently due to lots of programming for customer projects
- I think I should at least document how I am using timers so that I can refer people to this post when the question arises again and again.
- Explaining a simple thing to somebody else is the best way to train clarity in teaching.
Generally speaking timers are not instantiated but scheduled. The difference is that the SDK/OS takes care of their memory management and we only have to worry about whether or not we want them to fire. So we don’t need to ever release a timer, instead we invalidate it.