cocoa

问题 When I call the performSegueWithIdentifier in the completion block, if I do not wrap the call in a dispatch_async, it literally takes 10 seconds for the segue to actually happen. However, I can do other things without wrapping them in the same dispatch_async, such as doing core data work, or, logging "things"... Any insight as to how this works and why... I am lost. If this isn't the right place to ask something like this, I apologize. EKEventStore *store = [[EKEventStore alloc] init]; [store

问题 I was wondering if there was a simple way to "bounce" or scroll an NSTextField with text thats too long to display. For Example: ----------------------------- <-- scroll | This is a rather large pi | ..ece of text! ----------------------------- So in this example, the text would scroll to the end, showing the rest of the message, then back to the beginning where it will rest; basically giving the user a peak at all of the text. ----------------------------- This is a ra.. | ther large piece

问题 I'm trying to use cocoa to grab images from a webcam. I'm able to get the image in RGBA format using the QTKit and the didOutputVideoFrame delegate call, and converting the CVImageBuffer to a CIImage and then to a NSBitmapImageRep. I know my camera grabs natively in YUV, what I want is to get the YUV data directly from the CVImageBuffer, and proccess the YUV frame before displaying it. My question is: How can I get the YUV data from the CVImageBuffer? thanks. 回答1: You might be able to create

问题 I need to get the day of the week from an NSDate as a number. For example, if today is Thursday I should get number 4, if Friday then number 5. Does this functionality already exist? 回答1: As per your requirement the following codes give you '4' for today i.e. Thursday 13 Dec 2012 NSMutableDictionary *weeks=[NSMutableDictionary new]; [weeks setObject:@"1" forKey:@"Monday"]; [weeks setObject:@"2" forKey:@"Tuesday"]; [weeks setObject:@"3" forKey:@"Wednesday"]; [weeks setObject:@"4" forKey:@

问题 by default NSLog outputs a long string before the requested output, e.g: NSLog(@"Log message"); Outputs to the console: 2011-04-15 11:23:01.692 MyAppName[23160:903] Log message I know I can add the filename and line number to the log, but how do I get rid of all the date, time and app name that appears before the message? I find it really clutters the console in Xcode making it harder to find the information I'm after. 回答1: This is definitely the FIRST thing I do on a new project. NSLog(…)

问题 I noticed that in many community Objective-C classes and in Apple's frameworks they name some of the variables using a convention that prefixes variables with an underscore, such as: _name . What is the reason for having the underscore. Should I be doing this in my own classes? If so where and when should I use it? 回答1: In Cocoa, it's a convention to indicate the something is private and shouldn't be used externally. However, it's unofficial convention, particularly in light of wording like

问题 How can I get events when the Dock is showing or hiding? 回答1: You can get a notification if the dock is visible or not using Carbon. I do not know of any way to do it in Cocoa. (I haven't tested this; it's from the code here) Create your callback method: #import <Carbon/Carbon.h> static const EventTypeSpec appEvents[] = { { kEventClassApplication, kEventAppSystemUIModeChanged } }; OSStatus DockChangedHandler(EventHandlerCallRef inCallRef, EventRef event, void *userData) { OSStatus status =

问题 I am using a NSColorWell which is set to continuously update. I need to know when the user is done editing the control (mouse up) from the color picker in the color panel. I installed an event monitor and am successfully receiving mouse down and mouse moved messages, however NSColorPanel appears to block mouse up. The bottom line is that I want to add the final selected color to my undo stack without all the intermediate colors generated while the user is choosing their selection. Is there a

问题 I've been stuck on this one for a while. I'm trying to run a rails shell command from my cocoa application to create a news rails app. When I run ~/.rvm/gems/ruby-1.9.3-p194/gems/railties-3.2.3/bin/rails new projectname I'm able to create a new project. But if I run something like this NSString *path = @"~/.rvm/gems/ruby-1.9.3-p194/gems/railties-3.2.3/bin/rails"; NSString *script = [NSString stringWithFormat:@"%@ new ~/Desktop/testapp", path]; system([script UTF8String]); or this - (IBAction

问题 How do I get started with programming for the Apple infared remote control? To start with, I only intend to support one control, and one type of receiver, that on the current unibody MacBooks. What I mean by programming, is, how do I get started with writing an OSX, preferably Cocoa if there are APIs, app which intercepts commands from the control, and then sends commands to the OS. For example, as a start, I'd like to be able to simply pick up a key press from the remote control, and then