ios - Writing NSDictionary with custom objects to file -

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this question has answer here:

i have nsdictionary array of custom objects, called maclasses. try writing dict file, simple method:

- (void)writedicttofilewithcontent:(nsdictionary *)contentdict {     nsarray *paths = nssearchpathfordirectoriesindomains(nsdocumentdirectory, nsuserdomainmask, yes);     nsstring *documentsdirectory = [paths objectatindex:0];     nsstring *filepath = [documentsdirectory stringbyappendingpathcomponent:@"/userdata.txt"];       [contentdict writetofile:filepath atomically:yes];  }

and read using

- (nsdictionary *)readfromdict {     nsarray *paths = nssearchpathfordirectoriesindomains(nsdocumentdirectory, nsuserdomainmask, yes);     nsstring *documentsdirectory = [paths objectatindex:0];     nsstring *filepath = [documentsdirectory stringbyappendingpathcomponent:@"/userdata.txt"];      nsdictionary *contentdict = [nsdictionary dictionarywithcontentsoffile:filepath];      return contentdict; }

the array of objects i'm trying write custom nsobject, structured kinda this:

@interface maassignment : nsobject  @property (nonatomic, strong) nsdate *date; @property (nonatomic, strong) nsstring *assignmentname; @property (nonatomic, strong) nsnumber *totalpoints; @property (nonatomic, strong) nsnumber *recievedpoints; @property (nonatomic, strong) nsnumber *classaverage; @property (nonatomic, strong) nsnumber *extracredit; @property (nonatomic, strong) nsnumber *notgraded;

which represents class.

i earlier using arrays of nsstrings , nsnumbers, , read , write fine. when switched the maclass object returned empty dict when tried read.

this why: iphone - writing nsmutabledictionary file

what should write dict instead?

you need serialize custom objects, 1 way following, in custom class write following 2 methods encoding/decoding each property want persist, not sure if writetofile use this, know can create nsdata object , write file following method

     //archive dictionary , serializable objects nsdata        nsdata *serializeddata= [nskeyedarchiver archiveddatawithrootobject:mydict];  //unarchive      nsdata *mydata=[nsdata datawithcontentsoffile:appfile];      nsmutabledictionary* mydict= (nsmutabledictionary*)[nskeyedunarchiver unarchiveobjectwithdata:mydata];

here 2 methods need in custom objects:

- (void)encodewithcoder:(nscoder *)coder {     [coder encodeint:self.propone forkey:@"propone"];     [coder encodeobject:self.proptwo forkey:@"proptwo"];     ...  } // decode object archive - (id)initwithcoder:(nscoder *)coder {     self = [super init];     self.propone=[coder decodeintegerforkey:@"propone"];     self.proptwo=[coder decodeobjectforkey:@"proptwo"];      ..      return self; }

hope helps


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