SIGARBT error crashing app - iphone

Question

I built this calculator app in xcode 4.5 the digits work as expected but the operations ie (+,- ,c)worked once and never since they only return Nan and inf and the enter button always crashes the app and returns the error below.I built the UI in the storyboard and linked buttons to relevant methods
#autoreleasepool {
return UIApplicationMain(argc, argv, nil, NSStringFromClass([CalculatorAppDelegate
class]));
This is my CalculatorViewController.h
#import <UIKit/UIKit.h>
#interface CalculatorViewController : UIViewController
#property (weak, nonatomic) IBOutlet UILabel *display;
#end
This is my CalculatorViewController.m
#import "CalculatorViewController.h"
#import "CalculatorBrain.h"
#interface CalculatorViewController ()
#property(nonatomic) BOOL userIsInTheMidleOfEnteringANumber;
#property (nonatomic, strong)CalculatorBrain *brain;
#end
#implementation CalculatorViewController
#synthesize display = _display;
#synthesize userIsInTheMidleOfEnteringANumber =_userIsInTheMidleOfEnteringANumber;
#synthesize brain = _brain;
- (CalculatorBrain *)brain
{
if (!_brain)_brain=[[CalculatorBrain alloc]init];
return _brain;
}
- (IBAction)digitPressed:(UIButton *)sender
{
NSString *digit = sender.currentTitle;
if (self.userIsInTheMidleOfEnteringANumber){
self.display.text = [self.display.text stringByAppendingString:digit];
}
else {
self.display.text = digit;
self.userIsInTheMidleOfEnteringANumber=YES;
}
}
- (IBAction)enterPressed
{
NSLog(#"im hre");
[self.brain pushOperand:[self.display.text doubleValue]];
self.userIsInTheMidleOfEnteringANumber=NO;
}
- (IBAction)operationPresed:(UIButton *)sender
{
if (self.userIsInTheMidleOfEnteringANumber) [self enterPressed];
double result =[self.brain performOperation:sender.currentTitle];
NSString *resultString= [NSString stringWithFormat:#"%g",result];
self.display.text= resultString;
}
#end
This is my CalculatorBrain.h
#import <Foundation/Foundation.h>
#interface CalculatorBrain : NSObject
-(void)pushOperand:(double)operand;
-(double)performOperation:(NSString *)operation;
#end
This is my CalculatorBrain.m
#import "CalculatorBrain.h"
#interface CalculatorBrain()
#property (nonatomic,strong)NSMutableArray *operandStack;
#end
#implementation CalculatorBrain
#synthesize operandStack = _operandStack;
-(NSMutableArray *)operandStack
{
if (_operandStack== nil) _operandStack =[[NSMutableArray alloc] init];
return _operandStack;
}
-(void)pushOperand:(double)operand
{
[self.operandStack addObject:[NSNumber numberWithDouble:operand]];
}
-(double)popOperand
{
NSNumber *operandObject = [self.operandStack lastObject];
if (operandObject) [self.operandStack removeLastObject];
return [operandObject doubleValue];
}
-(double)performOperation:(NSString *)operation
{
double result=0;
//calculate result
if ([operation isEqualToString:#"+"])
{
result =[self popOperand]+ [self popOperand];
}
else if ([operation isEqualToString:#"*"])
{
result = [self popOperand] * [self popOperand];
}
else if ([operation isEqualToString:#"-"]) {
result = [self popOperand] - [self popOperand];
}
else if ([operation isEqualToString:#"/"]) {
result = [self popOperand] / [self popOperand];
}
[self pushOperand:result];
return result;
}
#end
Im working from an example and have followed all steps i dont understand what im doing wrong the enterPressed method does not have a type ie UIButton This is my console output
2013-05-17 15:05:15.221 Calculator[786:11303] im hre
2013-05-17 15:05:15.280 Calculator[786:11303] -[CalculatorViewController enterPressed:]: unrecognized selector sent to instance 0x922a620
2013-05-17 15:05:15.288 Calculator[786:11303] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[CalculatorViewController enterPressed:]: unrecognized selector sent to instance 0x922a620'
*** First throw call stack:
(0x1c8e012 0x10cbe7e 0x1d194bd 0x1c7dbbc 0x1c7d94e 0x10df705 0x16920 0x168b8 0xd7671 0xd7bcf 0xd6d38 0x4633f 0x46552 0x243aa 0x15cf8 0x1be9df9 0x1be9ad0 0x1c03bf5 0x1c03962 0x1c34bb6 0x1c33f44 0x1c33e1b 0x1be87e3 0x1be8668 0x1365c 0x1f0d 0x1e35)
libc++abi.dylib: terminate called throwing an exception
(lldb)
any help will b appreciated

Answer 1

Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[CalculatorViewController enterPressed:]: unrecognized selector sent to instance 0x922a620' is the answer here. Check if your have the method enterPressed:in your CalculatorViewController class. I'm sure it's somehow misspelled if not missing

Answer 2

Change method signature:
- (IBAction)enterPressed
to
- (IBAction)enterPressed:(id)sender

Answer 3

In your CalculatorViewController.m file replace
- (IBAction)enterPressed
to
- (IBAction)enterPressed:(UIButton *)sender

Answer 4

I had this exact same problem actually... I deleted the Enter button and recreated it and then it worked after. Good luck, I wanted to pull my hair out

Answer 5

There are many working answers out there below. The reason why you have ran into this issue is, the method which you have linked in your xib file against one of your button appear on xib, points to enterPressed: - A method with an argument (enterPressed followed by a colon), but you have coded a method without an argument (enterPressed), hence it leads to a crash. Code tried to find a method with an argument which you have linked in your xib file, but it didn't find it, leads to a crash saying - ' unrecognized selector sent to instance'
Hence just replace
- (IBAction)enterPressed
with this:
- (IBAction)enterPressed:(UIButton *)sender