0422 线程同步/同步锁防止脏数据

如果不加同步锁,代码如下:

#import "ViewController.h"

@interface ViewController ()
{
    NSInteger _money;
}

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    _money = 100;

    NSThread *t1 = [[NSThread alloc]initWithTarget:self selector:@selector(doThing) object:nil];
    NSThread *t2 = [[NSThread alloc]initWithTarget:self selector:@selector(doThing) object:nil];
    NSThread *t3 = [[NSThread alloc]initWithTarget:self selector:@selector(doThing) object:nil];
    NSThread *t4 = [[NSThread alloc]initWithTarget:self selector:@selector(doThing) object:nil];
    t1.name = @"我是--t1";
    t2.name = @"我是--t2";
    t3.name = @"我是--t3";
    t4.name = @"我是--t4";

    [t1 start];
    [t2 start];
    [t3 start];
    [t4 start];


}

-(void)doThing{

for(int i=0;i<3;i++){

[self getMoney:10];

}

}

-(void)getMoney:(NSInteger)money{

    // 查余额

    if(_money >= money){

        [NSThread sleepForTimeInterval:2];

        _money -= money;

        NSLog(@"%@----余额 : %ld",[NSThread currentThread],_money);

}

// 打印结果,有随机性: 明显脏数据