1.OC中

声明Block
.h文件中
  @interface notNetWorkView : UIView
  @property (nonatomic, copy) void(^notNetWorkBlock)();
  @end                                 

.m文件中
  UIButton *noNetBtn = [[UIButton alloc]initWithFrame:CGRectMake(0, 0, SCREEN_WIDTH, 39)];
  [noNetBtn addTarget:self action:@selector(noNetBtnClick:) forControlEvents:UIControlEventTouchUpInside];
  [self addSubview:noNetBtn];

- (void)noNetBtnClick:(UIButton *)send {
    if (self.notNetWorkBlock) {
        self.notNetWorkBlock();
    }
}

在需要使用的页面调用
self.netWorkNotConnectView.notNetWorkBlock = ^(){     
    JWNetworkNotConnectVC *CompletePersonData = [[UIStoryboard storyboardWithName:@"NetWorkConnect" bundle:nil] instantiateViewControllerWithIdentifier:@"NetworkNotConnect"];
    [weakSelf.navigationController pushViewController:CompletePersonData animated:YES];
 };

2.Swift中

import UIKit

typealias btnBlock = (Int) -> () //声明

class RolodexNav1: UIView {
    
    var btnBlock:btnBlock? //初始化
   
    @IBAction private func btnClick(_ sender: UIButton) {
        //tag: 1 排序 2 pop
        if self.btnBlock != nil {
            btnBlock!(sender.tag) //调用
        }
    }

}

3.案例一
block回调

UMengShareManage调用testFunction

UMengShareManage.testFunction(title,desc,shareBack: {(err:Error?) -> () in 
  //用err参数toDoSomething
})

testFunction回调block的实现细节
定义一个block类型,

typealias ShareBack = (Error?) -> ()

设置一个ShareBack类型block全局变量

static var shareBackBlock:ShareBack?

在数据处理完后用block把数据传出来

UMengShareManage.share(plattype: plattype, messageObject: messageObject, viewController: VC) { (data:Any?, error:Error?) in
 
            if shareBackBlock != nil {
                self.shareBackBlock!(error)
            }
}

在testFunction中执行全局block把数据放在shareBack block参数中传回去

UMengShareManage. testFunction(title:String?,desc:String?,shareBack:@escaping ShareBack){
   self.shareBackBlock = {(err:Error?) -> () in
            shareBack(err)
        }
})

4.案例二
swift中闭包回调把数据传过来