/*

 File: StockObserver.m

 Abstract: Implements a simple object to get stock symbols from the UI and

 register for notifications of price changes of that stock.

 Copyright (c) 2000-2004, Apple Computer, Inc., all rights reserved.

 */

/*

 IMPORTANT:  This Apple software is supplied to you by Apple Computer, Inc. ("Apple") in

 consideration of your agreement to the following terms, and your use, installation, 

 modification or redistribution of this Apple software constitutes acceptance of these 

 terms.  If you do not agree with these terms, please do not use, install, modify or 

 redistribute this Apple software.

 In consideration of your agreement to abide by the following terms, and subject to these 

 terms, Apple grants you a personal, non-exclusive license, under AppleÕs copyrights in 

 this original Apple software (the "Apple Software"), to use, reproduce, modify and 

 redistribute the Apple Software, with or without modifications, in source and/or binary 

 forms; provided that if you redistribute the Apple Software in its entirety and without 

 modifications, you must retain this notice and the following text and disclaimers in all 

 such redistributions of the Apple Software.  Neither the name, trademarks, service marks 

 or logos of Apple Computer, Inc. may be used to endorse or promote products derived from 

 the Apple Software without specific prior written permission from Apple. Except as expressly

 stated in this notice, no other rights or licenses, express or implied, are granted by Apple

 herein, including but not limited to any patent rights that may be infringed by your 

 derivative works or by other works in which the Apple Software may be incorporated.

 The Apple Software is provided by Apple on an "AS IS" basis.  APPLE MAKES NO WARRANTIES, 

 EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION THE IMPLIED WARRANTIES OF NON-INFRINGEMENT, 

 MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, REGARDING THE APPLE SOFTWARE OR ITS 

 USE AND OPERATION ALONE OR IN COMBINATION WITH YOUR PRODUCTS.

 IN NO EVENT SHALL APPLE BE LIABLE FOR ANY SPECIAL, INDIRECT, INCIDENTAL OR CONSEQUENTIAL 

 DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS 

 OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) ARISING IN ANY WAY OUT OF THE USE, 

 REPRODUCTION, MODIFICATION AND/OR DISTRIBUTION OF THE APPLE SOFTWARE, HOWEVER CAUSED AND 

 WHETHER UNDER THEORY OF CONTRACT, TORT (INCLUDING NEGLIGENCE), STRICT LIABILITY OR 

 OTHERWISE, EVEN IF APPLE HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

*/

#import "StockObserver.h"

extern void AddStockNotificationObserver(const void *observer, CFStringRef stockSymbol);

extern void RemoveStockNotificationObserver(const void *observer, CFStringRef stockSymbol);

extern void RemoveObserverForAllStocks(const void *observer);

@implementation StockObserver

// The callback, as an ObjC method. We put the data in the status area

- (void)stockChanged:(NSString *)stockSymbol newPrice:(double)newPrice {

    NSString *newLine = [NSString stringWithFormat:@"%@ new price: $%.2f\n", stockSymbol, newPrice];

    [[[stockNewsField textStorage] mutableString] appendString:newLine];

}

// The action methods for the "Add" / "Remove" buttons

- (void)addStock:(id)sender {

    NSString *stockSymbol = [stockSymbolField stringValue];

    AddStockNotificationObserver((void *)self, (CFStringRef)stockSymbol);

    [[[stockNewsField textStorage] mutableString] appendFormat:@"Now observing %@\n", stockSymbol];

}

- (void)removeStock:(id)sender {

    NSString *stockSymbol = [stockSymbolField stringValue];

    RemoveStockNotificationObserver((void *)self, (CFStringRef)stockSymbol);

    [[[stockNewsField textStorage] mutableString] appendFormat:@"Stopped observing %@\n", stockSymbol];

}

// When this object is deallocated, it should stop observing; thankfully there's a way to

// quickly remove all observe requests for a given observer

- (void)dealloc {

    RemoveObserverForAllStocks((void *)self);

    [super dealloc];

}

// To assure that this object is deallocated when the app is quitting, we

// listen to the applicationWillTerminate delegate method of the app.

// In more sophisticated, multi-doc apps, we would probably listen to the

// document being closed instead.

- (void)applicationWillTerminate:(NSNotification *)notification {

    [self release];

}

@end

// Callback from AddStockNotificationObserver(). We simply convert the callback

// into an ObjC message send to the right StockObserver object

void StockPriceChanged(void *observer, CFStringRef stockSymbol, double newPrice) {

    [(id)observer stockChanged:(NSString *)stockSymbol newPrice:newPrice];

}