Multi-threaded use of the real column-ticketing system

#import "ViewController.h"

@interface Viewcontroller ()

{

UILabel *showlable;

int curticketnum;

int saleticketnum;

NSString *salewindowname;

Nscondition *conditionclock;

}

@end

@implementation Viewcontroller

-(void) Viewdidload {

[Super Viewdidload];

// ticketing system divided into 3 windows sold simultaneously

default of one ticket

Curticketnum = 100;

UIButton *button = [UIButton buttonwithtype:uibuttontypecustom];

Button.frame = CGRectMake (100, 20, 150, 50);

[Self.view Addsubview:button];

[Button settitle:@ " Sell ticket " forstate:uicontrolstatenormal];

Button.backgroundcolor = [Uicolor Redcolor];

[Button addtarget:self action: @selector (Startsale) forcontrolevents:uicontroleventtouchupinside];

showlable = [[UILabel alloc]initwithframe:cgrectmake (0, 200, 375, 200)];

[Self.view addsubview:showlable];

Showlable.numberoflines = 3;

Showlable.textalignment = Nstextalignmentcenter;

Showlable.text = @ " remaining votes:+" ;

Showlable.font = [Uifont boldsystemfontofsize:20];

Showlable.backgroundcolor = [Uicolor Orangecolor];

}

// three windows to sell tickets at the same time

-(void) Startsale

{

// Initialize 3 threads Each of the threads is a window

Nsthread *firstwindow = [[Nsthread alloc]initwithtarget:self selector: @selector (saleticket) Object:nil];

Firstwindow.name = @ " ticketing < window 1>";

[Firstwindow start];

Nsthread *secondtwindow = [[Nsthread alloc]initwithtarget:self selector: @selector (saleticket) Object:nil];

Secondtwindow.name = @ " ticketing < window 2>";

[Secondtwindow start];

Nsthread *thirdwindow = [[Nsthread alloc]initwithtarget:self selector: @selector (saleticket) Object:nil];

Thirdwindow.name = @ " ticketing < window 3>";

[Thirdwindow start];

Nscondition is a wire lock (conditional lock)

Conditionclock = [[Nscondition alloc]init];

}

-(void) Saleticket

{

// not using the thread lock 3 threads (Windows) will also access the method of selling tickets when the remaining number of votes is 0 , other threads will continue to visit, not knowing that the remaining number of votes is 0 , continue to access the remaining number of votes there is a negative situation

// solve this problem can use the thread lock; only one thread is allowed to access it after the other thread accesses it.

while (Curticketnum > 0) {

// Use the thread lock to allow only one thread to fetch access

[Conditionclock Lock];

Salewindowname = [Nsthread currentthread].name;

[Nsthread sleepfortimeinterval:0.1];

current number of votes ( remaining )

Curticketnum-= 1;

number of votes sold

Saleticketnum = 100-curticketnum;

[Self Performselectoronmainthread: @selector (UpdateUI) Withobject:nil Waituntildone:yes];

if (Curticketnum > 0) {

[Conditionclock unlock];

}

}

}

// Update interface

-(void) UpdateUI

{

NSLog (@ " already sold %d tickets \ n The remaining %d tickets \ n The current sales window is:%@", Saleticketnum,curticketnum, Salewindowname);

Showlable.text = [NSString stringwithformat:@ " has sold %d tickets \ nthe remaining %d tickets \ n The current sales window is: %@ ", Saleticketnum,curticketnum,salewindowname];

}

-(void) didreceivememorywarning {

[Super didreceivememorywarning];

Dispose of any resources the can be recreated.

}

@end

Copyright NOTICE: This article for Bo Master original article, without Bo Master permission not reproduced.

Multi-threaded use of the real column-ticketing system