ios - Faster way to iterate through a large NSArray of dictionaries -


i created "invite friends" feature ios app i'm building. able add alphabetical sections a-z, iterating through large array, using nspredicate picking out names start b way z. saving them dictionary keys a-z.

everything works, opening view takes 7 seconds moment click "invite friends" button.

what can make load seamlessly or atleast make seem seamless users , improving design , code?

here code

-(void)testing {  nsmutablearray *stringname = [[nsmutablearray alloc] init];  (nsdictionary* item in self.tabledata) {     // self.user = item;     nsstring* firstname = [item objectforkey:@"firstname"];     [stringname addobject:firstname];       nspredicate *apredicate = [nspredicate predicatewithformat:@"self beginswith[c] 'a'"];     nsarray *beginwitha = [stringname filteredarrayusingpredicate:apredicate];      nspredicate *bpredicate = [nspredicate predicatewithformat:@"self beginswith[c] 'b'"];     nsarray *beginwithb = [stringname filteredarrayusingpredicate:bpredicate];      nspredicate *cpredicate = [nspredicate predicatewithformat:@"self beginswith[c] 'c'"];     nsarray *beginwithc = [stringname filteredarrayusingpredicate:cpredicate];      nspredicate *dpredicate = [nspredicate predicatewithformat:@"self beginswith[c] 'd'"];     nsarray *beginwithd = [stringname filteredarrayusingpredicate:dpredicate];      nspredicate *epredicate = [nspredicate predicatewithformat:@"self beginswith[c] 'e'"];     nsarray *beginwithe = [stringname filteredarrayusingpredicate:epredicate];      nspredicate *fpredicate = [nspredicate predicatewithformat:@"self beginswith[c] 'f'"];     nsarray *beginwithf = [stringname filteredarrayusingpredicate:fpredicate];      nspredicate *gpredicate = [nspredicate predicatewithformat:@"self beginswith[c] 'g'"];     nsarray *beginwithg = [stringname filteredarrayusingpredicate:gpredicate];      nspredicate *hpredicate = [nspredicate predicatewithformat:@"self beginswith[c] 'h'"];     nsarray *beginwithh = [stringname filteredarrayusingpredicate:hpredicate];      nspredicate *ipredicate = [nspredicate predicatewithformat:@"self beginswith[c] 'i'"];     nsarray *beginwithi = [stringname filteredarrayusingpredicate:ipredicate];      nspredicate *jpredicate = [nspredicate predicatewithformat:@"self beginswith[c] 'j'"];     nsarray *beginwithj = [stringname filteredarrayusingpredicate:jpredicate];      nspredicate *kpredicate = [nspredicate predicatewithformat:@"self beginswith[c] 'k'"];     nsarray *beginwithk = [stringname filteredarrayusingpredicate:kpredicate];      nspredicate *lpredicate = [nspredicate predicatewithformat:@"self beginswith[c] 'l'"];     nsarray *beginwithl = [stringname filteredarrayusingpredicate:lpredicate];      nspredicate *mpredicate = [nspredicate predicatewithformat:@"self beginswith[c] 'm'"];     nsarray *beginwithm = [stringname filteredarrayusingpredicate:mpredicate];      nspredicate *npredicate = [nspredicate predicatewithformat:@"self beginswith[c] 'n'"];     nsarray *beginwithn = [stringname filteredarrayusingpredicate:npredicate];      nspredicate *opredicate = [nspredicate predicatewithformat:@"self beginswith[c] 'o'"];     nsarray *beginwitho = [stringname filteredarrayusingpredicate:opredicate];      nspredicate *ppredicate = [nspredicate predicatewithformat:@"self beginswith[c] 'p'"];     nsarray *beginwithp = [stringname filteredarrayusingpredicate:ppredicate];      nspredicate *qpredicate = [nspredicate predicatewithformat:@"self beginswith[c] 'q'"];     nsarray *beginwithq = [stringname filteredarrayusingpredicate:qpredicate];      nspredicate *rpredicate = [nspredicate predicatewithformat:@"self beginswith[c] 'r'"];     nsarray *beginwithr = [stringname filteredarrayusingpredicate:rpredicate];      nspredicate *spredicate = [nspredicate predicatewithformat:@"self beginswith[c] 's'"];     nsarray *beginwiths = [stringname filteredarrayusingpredicate:spredicate];      nspredicate *tpredicate = [nspredicate predicatewithformat:@"self beginswith[c] 't'"];     nsarray *beginwitht = [stringname filteredarrayusingpredicate:tpredicate];      nspredicate *upredicate = [nspredicate predicatewithformat:@"self beginswith[c] 'u'"];     nsarray *beginwithu = [stringname filteredarrayusingpredicate:upredicate];      nspredicate *vpredicate = [nspredicate predicatewithformat:@"self beginswith[c] 'v'"];     nsarray *beginwithv = [stringname filteredarrayusingpredicate:vpredicate];      nspredicate *wpredicate = [nspredicate predicatewithformat:@"self beginswith[c] 'w'"];     nsarray *beginwithw = [stringname filteredarrayusingpredicate:wpredicate];      nspredicate *xpredicate = [nspredicate predicatewithformat:@"self beginswith[c] 'x'"];     nsarray *beginwithx = [stringname filteredarrayusingpredicate:xpredicate];      nspredicate *ypredicate = [nspredicate predicatewithformat:@"self beginswith[c] 'y'"];     nsarray *beginwithy = [stringname filteredarrayusingpredicate:ypredicate];      nspredicate *zpredicate = [nspredicate predicatewithformat:@"self beginswith[c] 'z'"];     nsarray *beginwithz = [stringname filteredarrayusingpredicate:zpredicate];            // dictionary     self.sectiondict = [[nsmutabledictionary alloc] init];      if (![beginwitha count] == 0) {         _sectiondict[@"a"] = beginwitha;     }     if (![beginwithb count] == 0) {         _sectiondict[@"b"] = beginwithb;     }     if (![beginwithc count] == 0) {         _sectiondict[@"c"] = beginwithc;     }     if (![beginwithd count] == 0) {         _sectiondict[@"d"] = beginwithd;     }     if (![beginwithe count] == 0) {         _sectiondict[@"e"] = beginwithe;     }     if (![beginwithf count] == 0) {         _sectiondict[@"f"] = beginwithf;     }     if (![beginwithg count] == 0) {         _sectiondict[@"g"] = beginwithg;     }     if (![beginwithh count] == 0) {         _sectiondict[@"h"] = beginwithh;     }     if (![beginwithi count] == 0) {         _sectiondict[@"i"] = beginwithi;     }     if (![beginwithj count] == 0) {         _sectiondict[@"j"] = beginwithj;     }     if (![beginwithk count] == 0) {         _sectiondict[@"k"] = beginwithk;     }     if (![beginwithl count] == 0) {         _sectiondict[@"l"] = beginwithl;     }     if (![beginwithm count] == 0) {         _sectiondict[@"m"] = beginwithm;     }      //     if (![beginwithn count] == 0) {         _sectiondict[@"n"] = beginwithn;     }     if (![beginwitho count] == 0) {         _sectiondict[@"o"] = beginwitho;     }     if (![beginwithp count] == 0) {         _sectiondict[@"p"] = beginwithp;     }     if (![beginwithq count] == 0) {         _sectiondict[@"q"] = beginwithq;     }     if (![beginwithr count] == 0) {         _sectiondict[@"r"] = beginwithr;     }     if (![beginwiths count] == 0) {         _sectiondict[@"s"] = beginwiths;     }     if (![beginwitht count] == 0) {         _sectiondict[@"t"] = beginwitht;     }     if (![beginwithu count] == 0) {         _sectiondict[@"u"] = beginwithu;     }     if (![beginwithv count] == 0) {         _sectiondict[@"v"] = beginwithv;     }     if (![beginwithw count] == 0) {         _sectiondict[@"w"] = beginwithw;     }     if (![beginwithx count] == 0) {         _sectiondict[@"x"] = beginwithx;     }     if (![beginwithy count] == 0) {         _sectiondict[@"y"] = beginwithy;     }     if (![beginwithz count] == 0) {         _sectiondict[@"z"] = beginwithz;     }   }      self.dictsectiontitles = [[self.sectiondict allkeys] sortedarrayusingselector:@selector(localizedcaseinsensitivecompare:)];   }

here other in call method.

-(void)viewwillappear:(bool)animated {       [self loaddata];  }  - (void)loaddata { [self.contactsmanager importcontacts:^(nsarray *contacts)  {      self.tabledata = contacts;       [self testing];      [self.tableview reloaddata];      nslog(@"contacts: %@",contacts);  }];  }

thanks!

you traversing entire array 26 times. need algorithm traverses once, building dictionary go along.

nsmutabledictionary *sectiondict = [nsmutabledictionary dictionary];  (nsstring *s in array) {     nsstring *firstletter = [s substringtoindex:1];      nsmutablearray *section = sectiondict[firstletter];     if (section == nil) {         section = [nsmutablearray array];         sectiondict[firstletter] = section;     }      section addobject:s]; }

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