CODEWITHSUNDEEP
ios
Peter Webb
Peter Webb

Reputation: 691

ios nsCoding set but not calling encodeWithCoder

I am trying to use NSCoding to save and recover application state. I haven't used it before.

In my app, the protocol methods encodeWithCoder and initWithCoder are never being called. I have prepared a simple test case with the same problem so hopefully somebody can tell me what I am doing wrong.

Here is my CodingTest.h file:

#import <Foundation/Foundation.h>

@interface CodingTest : NSObject <NSCoding>
- (void) saveData;
- (void) loadData;
- (id) init: (int) testValue;

@end

Here is CodingTest.m

#import "CodingTest.h"
@interface CodingTest()
@property int testInt;
@end

@implementation CodingTest
- (id) init: (int) testValue
{
  _testInt = testValue;
  return self;
}

-(void) loadData
{
  CodingTest *newTestClass = [NSKeyedUnarchiver unarchiveObjectWithFile:@"testfile"];
}

-(void) saveData
{
  [NSKeyedArchiver archiveRootObject:self toFile:@"testfile"];
}

- (void) encodeWithCoder:(NSCoder *)encoder {
  [encoder encodeInt:_testInt forKey:@"intValue"];
}

- (id)initWithCoder:(NSCoder *)decoder {   
  int oldInt = [decoder decodeIntForKey:@"intValue"];
  return [self init:oldInt];
}

@end

I call it as follows:

CodingTest *testCase = [[CodingTest alloc] init:27];
  [testCase saveData ];
  [testCase loadData];

init, saveData and loadData are all being called. But encodeWithEncoder and initWithCoder are never called. What am I doing wrong?

Upvotes: 0

Views: 408

Answers (1)

Peter Webb
Peter Webb

Reputation: 691

The problem is that "testfile" on its own is not a valid filename. If this is changed to "tmp/testfile" it works fine.

Interestingly, if you get the file name wrong on encode, it won't call the decode function, even though the decode call doesn't specify the file name.

Upvotes: 1

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