只要调用 alloc 程序就崩溃
Topus *t1 = [Topus sharedTopus];Topus *t2 = [Topus sharedTopus];NSLog(@"%p-----%p",t1,t2);// 地址一样Topus *t3 = [[Topus alloc]init];// 崩溃
来源: http://www.jianshu.com/p/f3a8d7be994a