ios-信号量

代码虽然不常 但是很重要#import "semaphoreController.h"@interface semaphoreController ()@end@implementation semaphoreController- (void)viewDidLoad {                [super viewDidLoad];            dispatch_semaphore_t semaphore = dispatch_semaphore_create(10);        for (int i = 0; i < 100; i++) {        dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT,0),^{                        //1.当前信号量-1            dispatch_semaphore_wait(semaphore, DISPATCH_TIME_FOREVER);                        NSLog(@"%d",i + 1);//            sleep(2); C语言中的 睡眠            [NSThread sleepForTimeInterval:3];//OC 中的                        //当前的信号量加1            dispatch_semaphore_signal(semaphore);                    });        // Do any additional setup after loading the view.}}/*#pragma mark - Navigation// In a storyboard-based application, you will often want to do a little preparation before navigation- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {    // Get the new view controller using [segue destinationViewController].    // Pass the selected object to the new view controller.}*/@end