NSOperation添加操作依賴和監聽
//創建隊列
NSOperationQueue *queue = [[NSOperationQueue alloc]init];
//封裝操作
NSBlockOperation *op1 = [NSBlockOperation blockOperationWithBlock:^{
NSLog(@"1-----------%@",[NSThread currentThread]);
}];
NSBlockOperation *op2 = [NSBlockOperation blockOperationWithBlock:^{
NSLog(@"2-----------%@",[NSThread currentThread]);
}];
NSBlockOperation *op3 = [NSBlockOperation blockOperationWithBlock:^{
NSLog(@"3-----------%@",[NSThread currentThread]);
}];
NSBlockOperation *op4 = [NSBlockOperation blockOperationWithBlock:^{
NSLog(@"4-----------%@",[NSThread currentThread]);
}];
op3.completionBlock = ^{//添加監聽，操作執行完畢後 回調
NSLog(@"op3執行完畢。。");
};
//添加操作依賴 4->3->2->1 // 添加操作依賴能控制多任務並發的執行順序，不能設置循環依賴,可以跨隊列添加依賴
[op3 addDependency:op4];
[op2 addDependency:op3];
[op1 addDependency:op2];
//添加到隊列中
[queue addOperation:op1];
[queue addOperation:op2];
[queue addOperation:op3];
[queue addOperation:op4];
執行結果：
2019-02-22 23:59:43.749883+0800 下載圖片[15917:488100] 4-----------<NSThread: 0x600000e28100>{number = 3, name = (null)}
2019-02-22 23:59:43.750367+0800 下載圖片[15917:488101] 3-----------<NSThread: 0x600000e34000>{number = 4, name = (null)}
2019-02-22 23:59:43.750513+0800 下載圖片[15917:488100] 2-----------<NSThread: 0x600000e28100>{number = 3, name = (null)}
2019-02-22 23:59:43.750654+0800 下載圖片[15917:488100] 1-----------<NSThread: 0x600000e28100>{number = 3, name = (null)}
NSOperation添加操作依賴和監聽