CODEWITHSUNDEEP
iosobjective-cnsdecimalnumber
Matt Douhan
Matt Douhan

Reputation: 2113

Why does this Creation of NSDecimalNumber crash?

I am downloading some values from a cloud service as JSON objects and assigning them to NSString objects as below

NSString *price = [orpObjectDict objectForKey:@"price"];
NSString *qty = [orpObjectDict objectForKey:@"qty"];

My debug output shows that both strings have values as below

NSLog(@"price: %@ <--> qty: %@", price, qty);

2017-04-17 16:29:05.665043 NWMobileTill[1490:730225] price: 6.95 <--> qty: 1

But the following creation of NSDecimalNumber using those NSStrings fail

NSDecimalNumber *priceNumber = [NSDecimalNumber decimalNumberWithString:price];
NSDecimalNumber *qtyNumber = [NSDecimalNumber decimalNumberWithString:qty];

017-04-17 16:29:05.665886 NWMobileTill[1490:730225] -[__NSCFNumber length]: unrecognized selector sent to instance 0x174226240
2017-04-17 16:29:05.668080 NWMobileTill[1490:730225] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSCFNumber length]: unrecognized selector sent to instance 0x174226240'
*** First throw call stack:
(0x1926fd1b8 0x19113455c 0x192704268 0x192701270 0x1925fa80c 0x19323658c 0x1932340f0 0x193234754 0x1000d9078 0x192cff1e8 0x192d17120 0x1931ebfb0 0x193130aa8 0x1931210a4 0x1931ee35c 0x1006c5218 0x1006d2aec 0x1006c8ce0 0x1006d4e2c 0x1006d4b78 0x19178f2a0 0x19178ed8c)
libc++abi.dylib: terminating with uncaught exception of type NSException

Why is this simple creation crashing?

Upvotes: 1

Views: 799

Answers (3)

Lalit kumar
Lalit kumar

Reputation: 2207

You are getting Number and you are write code as string

Please write as this code in string formate

 NSString *price = [NSString stringWithFormat:@"%@", orpObjectDict objectForKey:@"price"];
 NSString *qty = [ [NSString stringWithFormat:@"%@",orpObjectDict objectForKey:@"qty"];

or simply check

if [price isKindOfClass:[NSString class]]
{  // It is string
}
else if [price isKindOfClass:[NSNumber class]]
{
  // It is number
}

Upvotes: 2

Lookaji
Lookaji

Reputation: 1043

You can directly retrieve your object by keys using NSDecimalNumber:

NSDictionary*orpObjectDict = @{
                               @"price" : @(5.4),
                               @"qty" : @(2)
                               };
NSString *price = [orpObjectDict objectForKey:@"price"];
NSLog(@"string price %@", price);

NSString *qty = [orpObjectDict objectForKey:@"qty"];
NSLog(@"string qty %@", qty);

NSDecimalNumber*dPrice = [orpObjectDict objectForKey:@"price"];
NSLog(@"decimal price %@", dPrice);

NSDecimalNumber *dqty = [orpObjectDict objectForKey:@"qty"];
NSLog(@"decimal quantity %@", dqty);

the output is:

2017-04-17 10:46:12.932 test[2836:50653] string price 5.4
2017-04-17 10:46:12.932 test[2836:50653] string qty 2
2017-04-17 10:46:12.933 test[2836:50653] decimal price 5.4
2017-04-17 10:46:12.933 test[2836:50653] decimal quantity 2

You can always check return object types with isKindOfClass or isMemberOfClass the latter being more restrictive.

As a rule of thumb, make sure the dictionary contains the keys and its value it's not nil before assigning:

id value = dictionary[key];
if (value) {...}

or for a better check:

if (value && value != [NSNull null]) {...}

EDIT

I think Objective C types management is weaker than Swift's. Anyway using [NSDecimalNumber alloc] initWithString: method gives you the right instance.

NSDictionary*orpObjectDict = @{
                               @"price" : @"5.4",
                               @"qty" : @(2)
                               };
NSString* price = [orpObjectDict objectForKey:@"price"];
NSLog(@"string price %@", price);

NSDecimalNumber*decimalPrice = [[NSDecimalNumber alloc] initWithString:price];
if ([decimalPrice isMemberOfClass:NSDecimalNumber.class]) {
    NSLog(@"dqty is a NSDecimalNumber");
}

Upvotes: -1

vadian
vadian

Reputation: 285069

The error message

[__NSCFNumber length]: unrecognized selector sent to instance 0x174226240

is pretty clear: It reveals that the object for key price is an NSNumber object.

So you have to create an NSDecimalNumber from an NSNumber:

NSNumber *price = orpObjectDict[@"price"];
NSDecimalNumber *priceNumber = [NSDecimalNumber decimalNumberWithDecimal:price.decimalValue];

Upvotes: 0

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