iphone

How do I tell if a UIView is visible and on screen?

If I have a UIView (or UIView subclass) that is visible, how can I tell if it's currently being shown on the screen (as opposed to, for example, being in a section of a scroll view that is currently off-screen)? To maybe give you a better idea of what I mean, UITableView has a couple of methods for determining the set of currently visib...

Do I have a shot at learning Objective-C?

I do mostly ActionScript development, plus a bit of C# (and historically Lingo, Java and VB). What are my chances of learning Objective-C? I'd love to have a go at iPhone development, but the language just looks so insanely different to everything else. ...

How do you implement a Highpass filter for the IPhone accelerometer?

I remember seeing the code for a Highpass filter a few days back somewhere in the samples, however I can't find it anywhere now! Could someone remember me where the Highpass filter implementation code was? Or better yet post the algorithm? Thanks! ...

NSDateFormatter, am I doing something wrong or is this a bug?

I'm trying to print out the date in a certain format: NSDate *today = [[NSDate alloc] init]; NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init]; [dateFormatter setDateFormat:@"yyyyMMddHHmmss"]; NSString *dateStr = [dateFormatter stringFromDate:today]; If the iPhone is set to 24 hour time, this works fine, if on the other ...

How to display text using Quartz on the iPhone?

I've been trying to display text using a Quartz context, but no matter what I've tried I simply haven't had luck getting the text to display (I'm able to display all sorts of other Quartz objects though). Anybody knows what I might be doing wrong? example: -(void)drawRect:(CGRect)rect { // Drawing code CGContextRef context = UI...

How to get the RGB values for a pixel on an image on the iphone

I am writing an iPhone application and need to essentially implement something equivalent to the 'eyedropper' tool in photoshop, where you can touch a point on the image and capture the RGB values for the pixel in question to determine and match its color. Getting the UIImage is the easy part, but is there a way to convert the UIImage d...

Memory leak detection tools in XCode

Does Apple's Xcode development enviroment provide any tools for memory leak detection? I am especially interested in tools that apply to the iPhone SDK. (currently my favorite platfrom for hobby programming projects) Documentations/tutorials for said tools would be very helpful. ...

Reading call history in iPhone OS

I'm doing some research on the feasibility of an iPhone application, and can't find any indication in Apple's documentation that an iPhone app can read the call history of the phone, specifically the number/address book entry called, when, and the duration. Does anyone know if this is possible, and how? Note: The purpose is to remove t...

Distributing iPhone applications 2.1 vs 2.0

Can iPhone applications compiled against 2.1 be successfully installed via iTunes on a 2.0 device? I know iPhone applications compiled with 2.1 can run on a 2.0 device (assuming they're not using anything new from 2.1). But am not sure if iTunes will let the install take place. Does anyone have concrete information on this? I have not...

Which image format is cost effective in terms of network operation for iPhone?

I want to display a thumbnail image in a cell of table view controller,this thumbnail image is located at some remote place(URL of address is in XML file) so which format of image is cost effective? thanks in advance. ...

How Can I Get Touch Events in an iPhone App's Hidden Status Bar's Area?

I have an iPhone app that hides the status bar. However, my main view doesn't get any touch events when I tap in the status bar area. Is there something I can do to fix this? Here are a few details of my app's setup (in case it matters): It's an OpenGL-based application. The app launches in landscape mode. However, the touch events...

What #defines are setup by xCode when compiling for iPhone

I'm writing some semi-portable code and want to be able to detect when I'm compiling for iPhone. So I want something like #ifdef IPHONE_SDK.... Presumably xCode defines something, but I can't see anything under project properties, and google isn't much help. ...

Does iPhone support XML-RPC?

Does iPhone support XML-RPC, Is their any open source framework which I can use? Thanks in advance. ...

Easy way to scroll overflow text on a button?

Does anyone have any examples or resources where i might find information on scrolling text which is too long to display in a button control? I'm thinking something along these lines. Display as much text will fit within the current rect with a '...' at the end to signify overflow. Pause for say 1 second then slowly scroll the text to...

Change the resolution of image in iPhone?

I wanted to change the resolution of a image,this image I am getting from remote location.The image I am getting is too large to fit in iPhone screen is their any way to change that resolution? Thanks in advance ...

How do I detect when someone shakes an iPhone?

I want to react when somebody shakes the iPhone. I don't particularly care how they shake it, just that it was waved vigorously about for a split second. Does anyone know how to detect this? ...

Porting Android's Java VM to the iPhone?

Does anyone know of any existing projects that aim to port Android's Java VM over to the iPhone? From what I understand, this wouldn't be too out of reach and would certainly make for some exciting developments. Edit: I should point out that I am aware this will not happen using the official iPhone SDK. However, a jailbroken platform wo...

iPhone tab bar Item image resolution?

what is the resolution of the image for tab bar item? and also please provide some other usefull information regarding that tab item image. Thanks in advance. ...

Beginner Help for Developing Web Pages for Smart Phones

I have just started authoring web pages for use on "smart phones". I need to target Blackberry, WinCE, iPhone, etc. What resources or books would you recommend for someone with ample web and software development experience but no experience developing UI for these devices? What emulation kits would you recommend, and how accurately do...

What are best practices that you use when writing Objective-C and Cocoa?

I know about the HIG (which is quite handy!), but what programming practices do you use when writing Objective-C, and more specifically when using Cocoa (or CocoaTouch). ...