摘要：
#import "ViewController.h" @interface ViewController () @property (nonatomic,assign) int ticket; @end @implementation ViewController - (void)viewDidLo 阅读全文
摘要：
#define kSemaphoreBegin \ static dispatch_semaphore_t semaphore; \ static dispatch_once_t onceToken; \ dispatch_once(&onceToken, ^{ \ semaphore = disp 阅读全文