Objective c - trouble with Archiving encode and decode

Question

I am learning objective-c at the moment and up to the archiving and got stuck with encode and decode.

here is my code.

 #import <Foundation/Foundation.h>

    @interface Foo : NSObject<NSCoding>

    @property (copy, nonatomic) NSString *strVal;
    @property int intVal;
    @property float floatVal;

    @end

    #import "Foo.h"

@implementation Foo

@synthesize intVal, floatVal, strVal;

-(void) encodeWithCoder: (NSCoder *) encoder
{
    [encoder encodeObject: strVal forKey: @"test1"];
    [encoder encodeInt: intVal forKey: @"test2"];
    [encoder encodeFloat: floatVal forKey: @"test3"];
}

-(id) initWithCoder: (NSCoder *) decoder
{
    strVal = [decoder decodeObjectForKey: @"test1"];
    intVal = [decoder decodeIntForKey: @"test2"];
    floatVal = [decoder decodeFloatForKey: @"test3"];

    return self;
}

@end


    #import "Foo.h"

    int main (int argc, const char * argv[])
    {

        @autoreleasepool {
            Foo *myFoo1 = [[Foo alloc] init];
            Foo *myFoo2;

            [myFoo1 setStrVal : @"bill"];
            [myFoo1 setIntVal : 2];
            [myFoo1 setFloatVal: 3.4];

            [NSKeyedArchiver archiveRootObject: myFoo1 toFile: @"foo.arch"];

            myFoo2 = [NSKeyedUnarchiver unarchiveObjectWithFile: @"foo.arch"];

            NSLog(@"%@", [myFoo2 strVal]);
        }
        return 0;
    }

The decode works for int and float, however when i try to decode the NSString object. i got the following error and i have no clue about it...

Thread 1: programe received signal: EXC_BAD_ACESS"

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Answer 1

-initWithCoder: is an initialiser method, where you must call [super init] before setting up your object. See the example in Apple's "Archives and Seralizations Programming Guide".

Answer 2

Are you using ARC?

Regardless, you should copy all strings (strValue = [[decoder decodeObjectForKey:@"test1"] copy];), in order to keep an immutable reference to them. Otherwise, they can change or disappear behind your back and things will go kaboom (like you're seeing).

Also, like @一二三 said, don't forget to self = [super init];.