IPhone input/output stream asynchronously reads and writes data

1. First, write data to the file.

Writefile. h

# Import <Foundation/Foundation. h> # import <uikit/uikit. h> @ Class notedb; @ interface writefile: nsobject <nsstreamdelegate> {// file address nsstring * parentdirectorypath; // output stream, write data nsoutputstream * asyncoutputstream; // nsdata * outputdata; // nsange outputrange; // data source notedb * anotedb;} @ property (nonatomic, retain) nsdata * outputdata; @ property (nonatomic, retain) notedb * anotedb; // write data-(void) write; @ end

Implementation file writefile. m

# Import "writefile. H" # import "notedb. H" @ implementation writefile @ synthesize outputdata, anotedb;-(ID) Init {self = [Super init]; If (! Self) {[self release]; return nil;} outputdata = [[nsdata alloc] init]; anotedb = [[notedb alloc] init]; return self;}-(void) write {// nslog (@ "% @", self. anotedb); // sandbox path nsarray * paths = nssearchpathfordirectoriesindomains (nsdocumentdirectory, nsuserdomainmask, yes); nsstring * documentsdirectory = [paths objectatindex: 0]; // The file name is note.txt nsstring * Path = [documentsdirectory stringbyappendingpathcomponent: @ "Note.txt"]; [asyncoutputstream release]; parentdirectorypath = path; // data source nsdata * tmpdata = [nskeyedarchiver archiveddatawithrootobject: Self. anotedb. notelist]; // self. outputdata = [[nsdata alloc] initwithdata: tmpdata]; self. outputdata = tmpdata; // where to start outputrange. location = 0; // create the file [[nsfilemanager defaultmanager] createfileatpath: parentdirectorypathcontents: Nil attributes: Nil]; // initialize the output stream asyncoutput Stream = [[nsoutputstream alloc] inittofileatpath: parentdirectorypath append: No]; // callback method, [asyncoutputstream setdelegate: Self]; // asynchronous processing, [asyncoutputstream scheduleinrunloop: [nsunloop currentrunloop] formode: nsdefaultrunloopmode]; // open the asynchronous output stream [asyncoutputstream open];}-(void) stream :( nsstream *) thestream handleevent :( nsstreamevent) streamevent {// nslog (@ "as"); nsoutputstream * outputstream = (nsoutput Stream *) thestream; bool shouldclose = no; Switch (streamevent) {Case nsstreameventhasspaceavailable: // read event {// buffer uint8_t outputbuf [1]; // length outputrange. length = 1; // put the data in the buffer [outputdata getbytes: & outputbuf range: outputrange]; // put the content in the buffer into the output stream [outputstream write: outputbuf maxlength: 1]; // determine whether data has been read if (++ outputrange. location = [outputdata length]) {shouldclose = yes;} break;} case nsstreameventer Roccurred: {// when an error occurs, nserror * error = [thestream streamerror]; If (error! = NULL) {uialertview * erroralert = [[uialertview alloc] initwithtitle: [error localizeddescription] Message: [error details] delegate: Nil cancelbuttontitle: @ "OK" failed: Nil]; [erroralert show]; [erroralert release];} shouldclose = yes; break;} case nsstreameventendencountered: shouldclose = yes;} If (shouldclose) {// when an error occurs or data is written, remove the thread from [outputstream removefromrunloop: [nsunloop currentrunloop] formode: nsdefaultrunloopmode]; // finally turn off the output stream [thestream close];}-(void) dealloc {[outputdata release]; [anotedb release]; [Super dealloc] ;}@ end

2. Second, reading data from files

Readfile. h

# Import <Foundation/Foundation. h> @ Class notedb; @ interface readfile: nsobject <nsstreamdelegate> {// path nsstring * parentdirectorypath; // asynchronous output stream nsinputstream * asyncinputstream; // read data nsmutabledata * resultdata; // return the de-data notedb * anotedb;} @ property (nonatomic, retain) notedb * anotedb; @ property (nonatomic, retain) nsmutabledata * resultdata; // start to read data-(void) read; // append the read data to resultdata-(void) appenddata :( nsdata *) _ data; //-(void) dataatnotedb; // return the Retrieved Data-(notedb *) getnotedb; @ end

Implement file readfile. m

# Import "readfile. H "# import" notedb. H "# import" notelist. H "# import" writefile. H "@ implementation readfile @ synthesize anotedb, resultdata;-(ID) Init {self = [Super init]; // anotedb = [[notedb alloc] init]; resultdata = [[nsmutabledata alloc] init]; return self;}-(void) read {// sandbox path nsarray * paths = nssearchpathfordirectoriesindomains (nsdocumentdirectory, nsuserdomainmask, yes ); nsstring * documentsdirectory = [Pat HS objectatindex: 0]; // file name nsstring * Path = [documentsdirectory stringbyappendingpathcomponent: @ "note.txt"];/* If (! [[Nsfilemanager defaultmanager] fileexistsatpath: path]) {// if it does not exist, create writefile * file = [[writefile alloc] init];} else {nslog (@ "note.txt file");} */[asyncinputstream release]; parentdirectorypath = path; // asynchronous input stream initialization, and assign the address asyncinputstream = [[nsinputstream alloc] initwithfileatpath: parentdirectorypath]; // sets the proxy (callback method, delegate) [asyncinputstream setdelegate: Self]; // sets the thread, add a thread and create a thread: as the name suggests, runloop is a non-stop loop that keeps removing CHEC K input [asyncinputstream scheduleinrunloop: [nsunloop currentrunloop] formode: nsdefaultrunloopmode]; // open the thread [asyncinputstream open];} // append data-(void) appenddata :( nsdata *) _ DATA {[resultdata appenddata: _ data];} // callback method, non-stop execution-(void) stream :( nsstream *) thestream handleevent :( nsstreamevent) streamevent {bool shouldclose = no; nsinputstream * inputstream = (nsinputstream *) thestream; // nslog (@ "as"); Switch (streameven T) {Case nsstreameventhasbytesavailable: {// read data // read byte length nsmaxlength = 128; // buffer uint8_t readbuffer [maxlength]; // read data from the output stream, read nsinteger bytesread = [inputstream read: readbuffer maxlength: maxlength]; // If the length is greater than 0, append the data if (bytesread> 0) {// read data in the buffer into data nsdata * bufferdata = [[nsdata alloc] initwithbytesnocopy: readbuffer length: bytesread freewhendone: No]; // append data [self appenddata: Buffer Data]; // release drop Data [bufferdata release];} break;} case nsstreameventerroroccurred: {// An error occurred while reading nserror * error = [thestream streamerror]; if (error! = NULL) {uialertview * erroralert = [[uialertview alloc] initwithtitle: [error localizeddescription] Message: [error details] delegate: Nil cancelbuttontitle: @ "OK" failed: Nil]; [erroralert show]; [erroralert release];} shouldclose = yes; break;} case nsstreameventendencountered: {shouldclose = yes; // data is returned after reading the data [self dataatnotedb]; [thestream close];} break;} If (shouldclose) {// when the file is read or an error is read, remove the thread [inputstream removefromrunloop: [nsunloop currentrunloop] formode: nsdefaultrunloopmode]; // close the stream [thestream close];}-(void) dataatnotedb {anotedb = nil; anotedb = [[notedb alloc] init]; anotedb. notelist = [nskeyedunarchiver unarchiveobjectwithdata: resultdata]; // nslog (@ "% @", anotedb);/* For (id tmp in anotedb. notelist. notearray) {nslog (@ "tmp = % @", TMP);} */}-(notedb *) getnotedb {return self. anotedb;}-(void) dealloc {[anotedb release]; [resultdata release]; [Super dealloc];} @ end

OK! This blog is my own exercise. I have not explained many things clearly. Please forgive me!