Objective-C iPhone Programming Lesson 8 - Drag to Move

I show you how to make an app that allows the user to drag squares around. Download the code at the following URL:
http://jitsik.com/uploads/Macheads/SimpleDragging.zip

Category:

Science & Technology

Tags:

• mac
• apple
• iphone
• sdk
• programming
• motion
• touch
• mutlitouch
• classes
• UIView

[MatthewPerry2011]

How old are you?

[macheads101]

@MatthewPerry2011 I am 14

[seany242]

im trying to drag a CGRect inside a subview and when i set up the code it always drags from the top left corner. how can i make it drag from the center?

[macheads101]

@seany242 Before giving the coordinates to draw the CGRect, you need to subtract half of the width and height of the box. So, for instance, myRect.x -= (myRect.size.width / 2). Do the same for height.

[johnydee187]

hey dude when you make a tutorial on how to do an app is there anyway you can debug the app for memory leaks or problems?That way anyone following wont run in to problems later and not know how to fix em..I followed lots of tutorials and had no errors and the app runs fine but when i debug theres lots of problems that will result in crashes.which we all know apple will reject instantly.

[macheads101]

@johnydee187 Mainly the apps I show don't have leaks, since I release all of my things properly. In a few tutorials from now I think I will demonstrate some common problems that happen, and how to fix them.

[MatthewPerry2011]

@macheads101 OMG, it is good for you. You are doing great job practicing programing. I think you can become a famous man in the future. When I was in your age, I was playing wow, or doing something else stupid.

[mengyijing]

Hi, thanks a lot ! the tutorial helps soooo much!

can you teach me how to show the actual coordinate, i mean (x,y) when you put down the image view we drag?

Also, can you also explain on how to show the trach(path) when the object is moving? what method should I call?

[mengyijing]

what if the thing we dragged is not a View, but an image view with an image loaded in?

[mengyijing]

Helps a lot!! thx lOl

[tkdkickboxer]

@macheads101 After some searching I found the same wallpaper at deviantART. Thanks anyway. :)

[johnydee187]

@macheads101 ok cool man..