Objective C Help

I'm getting an error from Xcode 4.2.1 'Sending 'double' to parameter of incompatible type 'NSNumber'.
Please help.

the error occurs at the following (which can be found in position below)

for (NSNumber *aTransaction in europeTransactions) {
[europeBudget spendDollars: [aTransaction doubleValue]];
}​

The code goes like this...

Code:

#import <Foundation/Foundation.h>

@interface 

Budget : NSObject 

{
    float exchangeRate;
    double budget;
    double exchangeTransaction;
}

- (void) createBudget: (double) aBudget withExchangeRate: (float) anExchangeRate;
- (void) spendDollars: (NSNumber*) dollars;
- (void) chargeForeignCurrency: (double) foreignCurrency;

@end

@implementation 

Budget
- (void) createBudget: (double) aBudget withExchangeRate: (float) anExchangeRate {
    budget = aBudget;
    exchangeRate = anExchangeRate;        
}

- (void) spendDollars: (NSNumber*) dollars {
    budget -= [dollars doubleValue];
    NSLog(@"Converting %.2f US dollars into foreign currency leaves $%.2f", [dollars doubleValue], budget);
}

- (void) chargeForeignCurrency: (double) foreignCurrency {
    exchangeTransaction = foreignCurrency*exchangeRate;
    budget -= exchangeTransaction;
    NSLog(@"Charging %.2f in foreign currency leaves $%.2f", foreignCurrency, budget);
}

@end

int main (int argc, const char * argv[]) {    
    
double numberEuros = 100;
    
NSNumber *europeDollarTransaction = [[NSNumber alloc] initWithDouble:100];
NSNumber *europeDollarTransaction2 = [[NSNumber alloc] initWithDouble:200];
                                          
NSMutableArray *europeTransactions = [[NSMutableArray alloc] initWithCapacity:1];

[europeTransactions addObject:europeDollarTransaction];
[europeTransactions addObject:europeDollarTransaction2];
                                          
Budget *europeBudget = [Budget new];
                                          
[europeBudget createBudget:1000.00 withExchangeRate:1.2500];
    
for (NSNumber *aTransaction in europeTransactions) {
[europeBudget spendDollars: [aTransaction doubleValue]];
}
    
[europeBudget chargeForeignCurrency:numberEuros];
     
return 0;
}

 

Is this better?

Thanks for adding the codes snippets for me.

The message I'm getting from Xcode is pretty much exactly what you have said @mobilehaathi. I just don't understand how I can send it an NSNumber, instead of a double...That's confusing.

My NSNumber is a double.

I'm just starting out.

 

Much appreciated

Thank you so much!

I'm using 'Objective C for dummies' and I literally just copied the code in, as it is written in the book. The book is wrong!

My code works now, thanks to this thread. Thanks everyone. I was losing my rag!

Kind Regards

 

Thanks. This is the first book I've used so far, so this is a really helpful point.