I do not want to quiet him altogether. Just the dynamic class warning. I suspect it is because the compiler has noway of knowing what class it is going to be so it can not find the method declarations for said class.
Todd
Hi Todd
Thanks for your thanks. And for the link. Interesting.
Yes, Obj/C++ is really good stuff. It's a software gem. I've always thought it's kind of difficult to approach and learn. However I suspect that's just me. Too much C++ destroys the brain cells.
Anyway, the warnings from the compiler are well intended paranoia.
Several possibilities spring instantly to mind:
1) There's a command-line option to the compiler to say "stop being an old woman"
2) Perhaps there's a pragma to calm his fears
3) You can use a C cast [(MyClass*) theLetter doThis: data] ;
4) Cast it at birth MyClass* myClass = (MyClass*) [[NSClassFromString ....] ;
I don't know if there is compiler option to silence him. However I think you should avoid that because those warnings are very helpful for the detecting typos and stuff. They are really useful. I suspect option (4)'s the winner. I look forward to hearing what you find.
So I added a class and called it using:
id theLetter = [[NSClassFromString(chosenLetter) alloc] init];
All is good, and my dynamic class is loaded correctly, and methods from that class can be called. However, I needed to add empty methods to my controller to avoid compiler warnings. Warnings that the methods did not exist. Not really a big deal. But I was browsing the documentation and the recommended way to instantiate it is:
Class theLetter = [[NSClassFromString(chosenLetter) alloc] init];
But here the empty methods do not passify the compiler.....and I get method missing warnings at compile.
Both of the above lines works correctly, just get compiler warnings.
Any ideas?
Todd
Thank you very much for the response. That is exactly what I was looking for. After you told me what I was looking for I did a bit of research myself and found that term. The context in which I found it referenced was for making plug-ins, it all makes sense now! For the record here is a pretty good tutorial of plug-in architecture:
http://www.cocoacast.com/?q=node/175. Thank you for pointing me in the correct direction....I now have a lot more research to do.
Todd
Hi Sanjeev
I've had a little google into this matter. There is an on-line tutorial available at:
http://www.mulle-kybernetik.com/software/OCMock/
And I believe you can contact the author of the framework (directly or via a mailing list).
Hi Sanjeev
I don't know anything about this and I'm out of town this weekend (at the Napa Valley Marathon). If nobody else replies, I'll look at this next week.
ToddYou can indeed create objects at run time by name with the NSClassFromString method. Like this:id xxNumber = [[NSClassFromString(@"NSNumber") alloc] initWithInt:1234];NSLog("xxNumber = %s\n",[[xxNumber description]UTF8String]) ;Going home on the train last night I thought "Cocoa must do this". Although "the book" (Aaron Hillegass's book) talks about storing instances of class objects in the NIB, I don't see how that is possible. The NIB contains a serialization of an object which is created when the NIB is loaded. Therefore if the nib loader can create objects by name, we can also. For that matter I believe you can create classes at run-time. This very dynamic nature of Obj/C make it much more like JavaScript than C++. Obj/C++ is C++ and the system therefore provides both the 'compiler centric' C++ object model and a highly dynamic run-time object model like a scripting language.I wrote the following command-line program to play with this. RMNumber = RobinMillsNumber (just to make it different from NSNumber = NextStepNumber)#import <Foundation/Foundation.h>@interface RMNumber : NSObject{ int n_ ;}- (id) initWithInt : (int) n ;+ (id) helloWorld ;@end@implementation RMNumber+ (id) helloWorld { printf("RMNumber +helloWorld() says Hello world\n") ; return nil ;}- (id) initWithInt:(int) n { n_ = n*2 ; [super init]; return self ;}- (BOOL) respondsToSelector:(SEL)aSelector{ BOOL result = [super respondsToSelector: aSelector] ; NSString* methodName = NSStringFromSelector(aSelector) ; printf("RMNumber::respondsToSelector: %s result = %d\n",[methodName UTF8String],result) ; return result ;}- (NSString*) description { NSString* me = [super description] ; NSString* result = [[NSString alloc]initWithFormat:@"RMString : %@ myValue = %d",me,n_/2] ; return result ;}@endint main (int argc, const char * argv[]){ NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init]; // insert code here... printf("Hello, World!\n"); [RMNumber helloWorld] ; if ( argc >= 1 ) { int n = atoi(argc > 1 ? argv[1] : "911") ; NSNumber* nsNumber = [[NSNumber alloc]initWithInt:n] ; RMNumber* rmNumber = [[RMNumber alloc]initWithInt:n] ; printf("nsNumber = %s\n",[[nsNumber description]UTF8String]) ; NSLog(@"rmNumber = %@", rmNumber) ; printf("rmNumber = %s\n",[[rmNumber description]UTF8String]) ; id xxNumber = [[NSClassFromString(@"NSNumber") alloc] initWithInt:n*2]; printf("xxNumber = %s\n",[[xxNumber description]UTF8String]) ; id yyNumber = [[NSClassFromString(@"RMNumber") alloc] initWithInt:n*2]; printf("xxNumber = %s\n",[[yyNumber description]UTF8String]) ; } else { printf("syntax: maddog <string> [class]\n") ; } [pool drain]; return 0;}
My problem is I am getting an error:
OCMckObject[NSNumberFormatter]: expected method was not invoked:setAllowsFloats:YES
I have written following Code:
- (void) testReturnStringFromNumber
{
id mockFormatter = [OCMockObject mockForClass:[NSNumberFormatter class]];
StringNumber *testObject = [[StringNumber alloc] init];
[[mockFormatter expect] setAllowsFloats:YES];
[testObject returnStringFromNumber:80.23456];
[mockFormatter verify];
}
@implementation StringNumber
- (NSString *) returnStringFromNumber:(float)num
{
NSNumberFormatter *formatter = [[NSNumberFormatter alloc] init];
[formatter setAllowsFloats:YES];
NSString *str= [formatter stringFromNumber:[NSNumber numberWithFloat:num]];
[formatter release];
return str;
}
@end
Hi Robin,
I think you are answering my question. In your example, for example, you are trying to create an object from the 'Monday.m' class, correct? Again in your example, then later in the code I could call a method and it would use 'monday.m or tuesday.m or wednesday.m', according to today.. This simple example seems like a harder way of doing it until say, a new day was added to the week, then a new class with the same methods could be created and the existing code should still work on it, like a plug in.
I am sure I did this with PHP and it had something to do with literal, as in using the variable literally. But it escapes me now.
I may be thinking inside my own little box here also. This could very well be a BAD approach to my issue. I am trying to write "good" code and not stray too far from accepted practices. Please let me know if this is the wrong approach.
Thank you,
Todd
Hi Todd
This is an interesting question. I'm at work in California at the moment (on a Windows machine). I'll reply in more detail this evening. The basic answer however is that all objects are derived from a common base class (NSObject). You can call any method on any object because the run-time system looks up the method before dispatching to theobject.
Remember that Obj/C is C (and Obj/C++ is C++), so you can use a cast to keep the compiler quiet (however you can never fool the run-time system).
NSString* myString = (NSString*) [[NSObject alloc]init] ; When you call [myString capitalizedString] will fail because the run time system will ask myString if he has a method called 'capitalizedString' and he'll throw when he does not.
If you do:NSObject* notAString = [[NSObject alloc]init] ;
[notAString capitalizedString] ;
The compiler will complain (warn) that he isn't sure that notAString has a method called capitalizedString.
If you want to defer the allocation of objects totally until runtime, something like this:
NSString* today = @'Monday' ; // something you know at run time
NSObject myObject;
// the following syntax is wrong !!!!
myObject = [[today alloc]init] ; // create an object at run-time
I know I don't have the correct syntax for this - however I'm confident that this is possible.
I hope this sets you off in the right direction. Please let me know if I'm not answering the question that is in your mind!
How can I instantiate a class from a variable contents? For example:
I want to have classes called:
apple.com.h
apple.com.m
mac.com.h
mac.com.m
NSString *x="apple.com";
parseHTML = [[???? alloc] init];
How can I make an instance of apple.com.m without an if x="apple.com" statement? Like below:
parser = [[x alloc] init];
I believe the word is literal. I am trying to leave this 'open' so classes can be added as needed for different domains.
Thank you,
Todd
Whoo! What a simple mistake. Sometimes the answer is right there in front of you, I read through the docs and would have sworn I had it right.
Thank you very much,
Todd
I think you've omitted the error: argument in the signature of the API.
http://developer.apple.com/mac/library/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/Reference/NSString.html#//apple_ref/occ/clm/NSString/stringWithContentsOfURL:encoding:error:stringWithContentsOfURL:encoding:error:
Returns a string created by reading data from a given URL interpreted using a given encoding.
+ (id)stringWithContentsOfURL:(NSURL *)url encoding:(NSStringEncoding)enc error:(NSError **)error
The URL to read.
The encoding of the data at url.
If an error occurs, upon returns contains an NSError object that describes the problem. If you are not interested in possible errors, you may pass inNULL.
A string created by reading data from URL using the encoding, enc. If the URL can’t be opened or there is an encoding error, returns nil.
Can someone tell me why:
NSString *content = [NSString stringWithContentsOfURL:theURL encoding:NSASCIIStringEncoding];
is generating compile error:
warning: 'NSString' may not respond to '+stringWithContentsOfURL:encoding:'
(Messages without a matching method signature will be assumed to return 'id' and accept '...' as arguments.)
theURL is of type NSURL, and without the encoding bit, it works....kind of. Returns garbage, which I assume is due to incorrect encoding.
Thanks a bunch,
Todd
It's what I believe too, there is certainly ODBC support somewhere but i didn't find anything about this.
If someone have informations about it ....
Thx
I believe there is ODBC support both on the Mac and in Cocoa. Obj/C is C (and Obj/C++ is C++) and the Mac is a UNIX machine. So if you have existing UNIX code to access the IBM i5, you should be able to build and use that with Cocoa. However, I personally have never done this and so I can't say anything about the difficulty involved.
Hi,
Is it possible to access IBM i5 (AS/400) databases from Objective-C ?
Thx
Hi Raz
Right. Don't shoot me, I'm only the messenger. It's the piano keys! I don't see this in the book - however if you uncheck the 'Alternating Rows' in InterfaceBuilder on your TableView - it works! Table View Attributes (between Highlight and Col. Sizing) Top/Right of Center in the screenshot:
If this works for you AND you can't see this in Aaron's book either, perhaps you'd like to send him an email. I'm sure he'll be pleased to hear about this (if he hasn't already). I've heard folk say Aaron is very friendly and helpful. Maybe the piano keys arrived with 3.2 or something (I don't remember).
If you're wondering how I found this, then I used the usual divide and conquer strategy. I messed about for an hour or so in the debugger, using defaults read and the sample/solution code. Then I came to the conclusion "there's something in the NIB that's telling him to ignore setBackgroundColor". 2 minutes later it was fixed. The only fun part of debugging anything is the last two minutes when the pain stops.
Here's a 'no thrills' method of doing it. It simply inspects the address.
- (IBAction) go : (id) sender
{
NSString* address = [ addressField stringValue] ;
NSLog(@"%@",address) ;
// sniff for http:// and if missing, update the UI and the address
NSString* http = @"http://" ;
UInt http_l = [http length];
bool bHttp = [address length] > http_l ;
if ( bHttp ) bHttp = [[address substringToIndex:http_l]
caseInsensitiveCompare: http] == NSOrderedSame;
if (!bHttp ) {
// update the UI
NSString* newAddress = [[NSString alloc]initWithFormat:@"%@%@",http,address] ;
[addressField setStringValue:newAddress];
[newAddress release] ;
// reread address from the control
address = [ addressField stringValue] ;
NSLog(@"rewritten as %@",address) ;
}
// display the address in the webview
[[webView mainFrame] loadRequest:
[NSURLRequest requestWithURL:[NSURL URLWithString: address ]
]];
}
it was a little bit hard, but I figured the tutorial out.
one question, how do I make the text say http:// when the user doesn't enter that?
I remember something about that in windows programming, but this one is kinda hard to figure out if you don't know what you're doing, because no programming is used to make it work.
Oh, you're still stuck. That's not so good. I'm out of town at the Python Conference in Atlanta this weekend and my iMac is at home. I'll have a look at the zip when I get home on Monday.
I'm not 'unstuck' as it seems. I can't see what's wrong here. I think what I will do is just start over and be more careful. Thank for the link to the book's code though...
You've lost me! You're in world that I've never entered.
Of course, another reader might be able to assist, however I'll be surprised because this forum is mostly about people getting started with Cocoa/ObjC on the desktop. So, while I encourage you to hang around here, I also recommend that you make the same request on a Ruby Forum or a Mac forum such as forums.macosxhints.com
When you find more about this, I hope you'll update this thread. The Cocoa environment is expanding from the Desktop into both the scripting world (Python and Ruby) and new devices (the iPhone and the soon to be iPad). I wish you every success in facing these challenges and I'll be delighted to hear about your adventures.
Hi -- I'm getting into Cocoa from the Ruby world, and was wondering if anyone is using any BDD technologies with Objective C and Cocoa (& Touch/Cocoa) that they could recommend?
In Ruby, I love the mix of Cucumber and RSpec, and whilst I know these can be used with Cocoa, I'd like to know what else is out there that works best with it.
Cheers,
Doug.
Hi M
Take a look at the code for Aaron Hillegass' book. You can download it from here: http://www.bignerdranch.com/solutions/Cocoa-3rd.tgz
in 10_Defaults/RaiseMan_B he has code that works with preferences. I think you're trying to override a preference and I was able to do that in AppController.m (see below - I've added one line to set the background color to Blue).
If you don't have a copy of his book, I strongly encourage you to purchase it. When I arrived in Cocoa land as a refugee from MFC and Windows, I was really lost and puzzled by the landscape. I would have starved to death without that book.
I'm not certain that I've really answered your question, however I'm sure you'll be able to use Aaron's code to get to the bottom of this.
- (BOOL)applicationShouldOpenUntitledFile:(NSApplication *)sender
{
NSLog(@"applicationShouldOpenUntitledFile:");
[[NSUserDefaults standardUserDefaults] setObject:[NSKeyedArchiver archivedDataWithRootObject:[NSColor blueColor]] forKey:BNRTableBgColorKey];
return [[NSUserDefaults standardUserDefaults] boolForKey:BNREmptyDocKey];
}
Yeah- that's the reason I bought the book was because of it's reviews. Thanks for the link- it's just what I needed 
I'm sorry to hear you are stuck. That's a really good book and everybody agrees it's the best way to learn Cocoa. The code/solutions are available from http://www.bignerdranch.com/solutions/Cocoa-3rd.tgz Build and run the solution. If the solution works, and your code doesn't - maybe you'll find the fix by inspection.
It does say on p197 "Only windows created after the change will be affected" - so are you sure this isn't user error. And use the defaults command (page 208) to be sure the color preference is being stored.
Please let me know if you're 'unstuck', otherwise I'll take a look at your zip on Sunday afternoon (I'm in California).
I have a preferences panel that has a popup button that I bound to the Shared User Defaults system. I used the selectedValue and it seems to work, except on the initial launch of the app it is set to nothing. I set up default values on in an init method:
- (id)init
{
[super init];
NSMutableDictionary * defaultPrefs = [NSMutableDictionary dictionary];
[defaultPrefs setObject:@"navDevice" forKey:@"TomTom"];
prefs = [[NSUserDefaults standardUserDefaults] retain];
[prefs registerDefaults:defaultPrefs];
return self;
}
What I want to do now is set the selected item of the popup (navDevicePref) to @"TomTom". Something like:
[navDevicePref ?????:[prefs stringForKey:@"navDevice"]];
I read through the class description and tried various set... methods and none work in the awake from nib method of my controller.
Todd
Hello,
This is my first post and I am trying to learn Cocoa. I'm working my way through this book and I am stuck on a very specific problem.
I am using 10.6.2 and XCode 3.21 which is a little newer than the book I have.
In chapter 12, you work on an application called RaiseMan which is just a simple application that has a list of people and their raises. It's a Document based application and I have the undo, save and open and basically everything working except one part.
The preferences panel has two options: a checkbox and a colorwell. The checkbox sets defaults that determines if a new document is opened on startup. The colorwell sets the background colour of the tableview control on the main document.
The checkbox is working, the colorwell is not. At least, the color well is setting the color and saving it to the preferences- you can see this when you open the application because the previous color is saved and reloaded. It's supposes to change the table views background while the app is running.
I can't see what I missed and the program is compiling with no errors.
I've been stuck on this for over a week...
I've uploaded my entire project and wondered if someone would look at it??
Attachment: RaiseMan2.zip (2356.0KB)
Hi MadDog
Are you saying you're OK - or are you expecting a reply on this one?
