A.BOOL executing;//判斷任務(wù)是否正在執(zhí)行 B.BOOL finished;//判斷任務(wù)是否完成 C.void(^completionBlock)(void);//用來設(shè)置完成后需要執(zhí)行的操作 D.-(void)waitUntilFinished;//取消任務(wù)
A.[operation1 addDependency:operation2]; B.[operation addExecutionBlock:^{}]; C.[operation waitUntilFinished]; D.[operation cancel];