iOS reads large files on one line

DDFileReader.h

@interface Ddfilereader:nsobject {NSString * filePath;
    Nsfilehandle * FILEHANDLE;
    unsigned long long currentoffset;

    unsigned long long totalfilelength;
    NSString * Linedelimiter;
Nsuinteger chunksize;
} @property (nonatomic, copy) NSString * linedelimiter;

@property (nonatomic) Nsuinteger chunksize;

-(ID) Initwithfilepath: (NSString *) Apath;
-(NSString *) readLine;

-(NSString *) readtrimmedline;
#if ns_blocks_available-(void) Enumeratelinesusingblock: (void (^) (nsstring*, BOOL *)) block; #endif @end//ddfilereader.m #import "DDFileReader.h" @interface NSData (ddadditions)-(Nsrange) Rangeofdata_dd: (NS

Data *) Datatofind; @end @implementation NSData (ddadditions)-(Nsrange) RANGEOFDATA_DD: (NSData *) datatofind {const void * bytes = [s
    Elf bytes];

    Nsuinteger length = [self length];
    const void * searchbytes = [Datatofind bytes];
    Nsuinteger searchlength = [Datatofind length];

    Nsuinteger searchindex = 0; Nsrange Foundrange= {nsnotfound, searchlength}; for (Nsuinteger index = 0; index < length; index++) {if ((char *) bytes) [Index] = = ((char *) searchbytes) [Searc
                Hindex]) {//the current character matches if (foundrange.location = = Nsnotfound) {
            foundrange.location = index;
            } searchindex++;
        if (Searchindex >= searchlength) {return foundrange;}
            else {searchindex = 0;
        Foundrange.location = Nsnotfound;
} return Foundrange;

@end @implementation ddfilereader @synthesize linedelimiter, chunksize; -(ID) Initwithfilepath: (NSString *) Apath {if (self = [super init]) {filehandle = [Nsfilehandle filehandlefo
        Rreadingatpath:apath];
        if (FileHandle = = nil) {[Self release]; return nil;
        } linedelimiter = [[NSString alloc] initwithstring:@ "\ n"];
        [FileHandle retain];
        FilePath = [Apath retain]; CurreNtoffset = 0ULL;
        Chunksize = 10;
        [FileHandle Seektoendoffile];
        Totalfilelength = [FileHandle offsetinfile];
    We don ' t need to seek the back, since ReadLine'll do.
return self;
    }-(void) Dealloc {[FileHandle closefile];
    [FileHandle release], filehandle = nil;
    [FilePath release], FilePath = nil;
    [Linedelimiter release], linedelimiter = nil;
    Currentoffset = 0ULL;
[Super Dealloc];

    }-(NSString *) ReadLine {if (currentoffset >= totalfilelength) {return nil;}
    NSData * Newlinedata = [Linedelimiter datausingencoding:nsutf8stringencoding];
    [FileHandle Seektofileoffset:currentoffset];
    Nsmutabledata * CurrentData = [[Nsmutabledata alloc] init];

    BOOL Shouldreadmore = YES;
    NSAutoreleasePool * Readpool = [[NSAutoreleasePool alloc] init];
        while (Shouldreadmore) {if (Currentoffset >= totalfilelength) {break;}
    NSData * chunk = [FileHandle readdataoflength:chunksize];    Nsrange Newlinerange = [Chunk rangeofdata_dd:newlinedata]; 
            if (newlinerange.location!= nsnotfound) {//include The length so we can include the delimiter in the string
            chunk = [Chunk subdatawithrange:nsmakerange (0, Newlinerange.location+[newlinedata length])];
        Shouldreadmore = NO;
        } [CurrentData Appenddata:chunk];
    Currentoffset + = [chunk length];

    [Readpool release];
    NSString * line = [[NSString alloc] Initwithdata:currentdata encoding:nsutf8stringencoding];
    [CurrentData release];
return [line autorelease]; }-(NSString *) readtrimmedline {return [[self readLine] stringbytrimmingcharactersinset:[nscharacterset whitespace
Andnewlinecharacterset]];
  #if ns_blocks_available-(void) Enumeratelinesusingblock: (void (^) (nsstring*, bool*)) block {NSString * line = nil;
  BOOL stop = NO;
  while (stop = NO && (line = [self readLine])) {Blocks (line, &stop); }} #endif @end If Your file is small, then @mipadi ' s method would probably be just fine. However, if your file is large (> 1MB, perhaps?), then your may want to consider reading the file line-by-line. I wrote a class once to did that, which I ' ll paste here://ddfilereader.h @interface ddfilereader:nsobject {Nsstrin

    G * FILEPATH;
    Nsfilehandle * FILEHANDLE;
    unsigned long long currentoffset;

    unsigned long long totalfilelength;
    NSString * Linedelimiter;
Nsuinteger chunksize;
} @property (nonatomic, copy) NSString * linedelimiter;

@property (nonatomic) Nsuinteger chunksize;

-(ID) Initwithfilepath: (NSString *) Apath;
-(NSString *) readLine;

-(NSString *) readtrimmedline;
#if ns_blocks_available-(void) Enumeratelinesusingblock: (void (^) (nsstring*, BOOL *)) block; #endif @end//ddfilereader.m #import "DDFileReader.h" @interface NSData (ddadditions)-(Nsrange) Rangeofdata_dd: (NS

Data *) Datatofind; @end @implementation NSData (ddadditions)-(Nsrange) Rangeofdata_DD: (NSData *) datatofind {const void * bytes = [self bytes];

    Nsuinteger length = [self length];
    const void * searchbytes = [Datatofind bytes];
    Nsuinteger searchlength = [Datatofind length];

    Nsuinteger searchindex = 0;
    Nsrange Foundrange = {nsnotfound, searchlength}; for (Nsuinteger index = 0; index < length; index++) {if ((char *) bytes) [Index] = = ((char *) searchbytes) [Searc
                Hindex]) {//the current character matches if (foundrange.location = = Nsnotfound) {
            foundrange.location = index;
            } searchindex++;
        if (Searchindex >= searchlength) {return foundrange;}
            else {searchindex = 0;
        Foundrange.location = Nsnotfound;
} return Foundrange;

@end @implementation ddfilereader @synthesize linedelimiter, chunksize; -(ID) Initwithfilepath: (NSString *) Apath {if (self = [super init]) {filehandle = [NsfilehandLe Filehandleforreadingatpath:apath];
        if (FileHandle = = nil) {[Self release]; return nil;
        } linedelimiter = [[NSString alloc] initwithstring:@ "\ n"];
        [FileHandle retain];
        FilePath = [Apath retain];
        Currentoffset = 0ULL;
        Chunksize = 10;
        [FileHandle Seektoendoffile];
        Totalfilelength = [FileHandle offsetinfile];
    We don ' t need to seek the back, since ReadLine'll do.
return self;
    }-(void) Dealloc {[FileHandle closefile];
    [FileHandle release], filehandle = nil;
    [FilePath release], FilePath = nil;
    [Linedelimiter release], linedelimiter = nil;
    Currentoffset = 0ULL;
[Super Dealloc];

    }-(NSString *) ReadLine {if (currentoffset >= totalfilelength) {return nil;}
    NSData * Newlinedata = [Linedelimiter datausingencoding:nsutf8stringencoding];
    [FileHandle Seektofileoffset:currentoffset]; Nsmutabledata * CurrentData = [[Nsmutabledata alloc] IniT];

    BOOL Shouldreadmore = YES;
    NSAutoreleasePool * Readpool = [[NSAutoreleasePool alloc] init];
        while (Shouldreadmore) {if (Currentoffset >= totalfilelength) {break;}
        NSData * chunk = [FileHandle readdataoflength:chunksize];
        Nsrange Newlinerange = [Chunk rangeofdata_dd:newlinedata]; 
            if (newlinerange.location!= nsnotfound) {//include The length so we can include the delimiter in the string
            chunk = [Chunk subdatawithrange:nsmakerange (0, Newlinerange.location+[newlinedata length])];
        Shouldreadmore = NO;
        } [CurrentData Appenddata:chunk];
    Currentoffset + = [chunk length];

    [Readpool release];
    NSString * line = [[NSString alloc] Initwithdata:currentdata encoding:nsutf8stringencoding];
    [CurrentData release];
return [line autorelease]; }-(NSString *) readtrimmedline {return [[self readLine] stringbytrimmingcharactersinset:[nscharacterset whitespace AndneWlinecharacterset]];
  #if ns_blocks_available-(void) Enumeratelinesusingblock: (void (^) (nsstring*, bool*)) block {NSString * line = nil;
  BOOL stop = NO;
  while (stop = NO && (line = [self readLine])) {Blocks (line, &stop); }} #endif @end

Then to use this, and you ' d do: Ddfilereader * reader = [[Ddfilereader alloc] initwithfilepath:pathtomyfile]; NSString * line = nil; while (line = [reader readLine])) { NSLog (@ ' read line:%@ ', line); } [Reader release]; Or (for 10.6+ and IOS 4+): ddfilereader * reader = [[Ddfilereader alloc] initwithfilepath:pathtomyfile]; [Reader enumeratelinesusingblock:^ (NSString * line, BOOL * stop) { NSLog (@ ' read line:%@ ', line); }]; [Reader release];

Http://stackoverflow.com/questions/3707427/how-to-read-data-from-nsfilehandle-line-by-line?lq=1