Swift: 比较Swift中闭包传值、OC中的Block传值

一、介绍

开发者对匿名函数应该很清楚,其实它就是一个没有名字的函数或者方法,给人直观的感觉就是只能看到参数和返回值。在iOS开发中中,它又有自己的称呼,在OC中叫Block代码块,在Swift中叫闭包(Closure)函数。在我个人看来,两者并没有什么太大不同,定义和实现方式差不多,只不过是名称不一样罢了。由于开发用的比较多,所以我就针对OC和Swift分别写一下他们的传值方式,加深印象。

 

二、需求

定义两个控制器分别为FirstViewController和SecondViewController,在FirstViewController中定义闭包或者block,在Push到第二个控制器SecondViewController后,点击SecondViewController的屏幕触发闭包或者block,打印闭包或者block传递过来的值。

 

三、步骤

  • 声明闭包或者block别名
  • 定义闭包或者block属性
  • 定义触发闭包的函数/方法
  • 定义传值的函数/方法

 

四、测试

1、Swift:闭包Closure

FirstViewController.swift

import UIKit

/**
 *  声明一个闭包别名,闭包含字符串类型的两个参数,无返回值(使用“()”或者“Void”都一样)
 */
typealias SwiftClosure = (name:String,age:Int) -> Void

class FirstViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        self.view.backgroundColor = UIColor.whiteColor()
        
     //创建push按钮 let button
= UIButton.init(frame: CGRectMake(200, 200, 100, 100)) button.setTitle("Push", forState: .Normal) button.center = self.view.center button.backgroundColor = UIColor.greenColor() button.setTitleColor(UIColor.redColor(), forState: .Normal) button.addTarget(self, action: #selector(PushSecondViewController), forControlEvents: .TouchUpInside) self.view.addSubview(button) } /** * 定义闭包属性,可选类型 */ var callBackClosure = SwiftClosure?() /** * 定义触发闭包调用的方法,此时需要将要传递的参数存入闭包中 * 此处我将参数固定死了,开发中根据需要自己可以将需要的数值当做方法的参数,其实就是给方法添加参数即可,由外部决定参数值 * 例如: func TriggerClosure(name:String,age:Int) -> Void { } */ func TriggerClosure(){ if callBackClosure != nil { callBackClosure!(name:"夏远全",age:26) } } /** * 闭包触发调用后,对闭包属性赋值,同时提供调用外部访问闭包中数值的接口 */ func callBackClosureFunction(closure:SwiftClosure){ callBackClosure = closure } /** * Push第二个控制器入栈 */ func PushSecondViewController() -> Void { self.navigationController?.pushViewController(SecondViewController(), animated: true) } }

SecondViewController.swift

import UIKit

class SecondViewController: UIViewController {

    /**
     *  创建第一个控制器实例
     */
    let firstVC = FirstViewController()
    
    
    override func viewDidLoad() {
        super.viewDidLoad()
        self.view.backgroundColor = UIColor.purpleColor()
        
        /**
         * 接收闭包触发后回传的数值并打印
         */
        firstVC.callBackClosureFunction { (name, age) in
            print("name:\(name), age:\(age)")
        }
    }
    
    /**
     *  点击屏幕触发闭包
     */
    override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {
        firstVC.TriggerClosure()
    }
    
}

点击演示结果如下,每一次点击都会触发闭包打印数据:

name:夏远全, age:26
name:夏远全, age:26
name:夏远全, age:26
name:夏远全, age:26
..................

 

 

2、OC:Block代码块

FirstViewController.h

#import <UIKit/UIKit.h>

/**
 *  声明一个block别名,block含字符串类型的两个参数,无返回值
 */
typedef void (^OCBlock)(NSString *name,NSInteger age);

@interface FirstViewController : UIViewController

/**
 *  触发block
 */
-(void)TriggerBlock;

/**
 *  block回调
 */
-(void)callBackBlockFunction:(OCBlock) block;

@end

FirstViewController.m

#import "FirstViewController.h"
#import "SecondViewController.h"



@interface FirstViewController ()
/**
 *  定义block属性
 */
@property (copy,nonatomic)OCBlock callBackBlock;
@end

@implementation FirstViewController

- (void)viewDidLoad {
    [super viewDidLoad];
 
    //创建push按钮
    UIButton *button = [[UIButton alloc] initWithFrame:CGRectMake(200, 200, 100, 100)];
    [button setTitle:@"Push" forState:UIControlStateNormal];
    [button setTitleColor:[UIColor greenColor] forState:UIControlStateNormal];
    [button setBackgroundColor:[UIColor redColor]];
    [button addTarget:self action:@selector(PushSecondViewController) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:button];
}

/**
 *  Push第二个控制器入栈
 */
-(void)PushSecondViewController{
    [self.navigationController pushViewController:[[SecondViewController alloc] init] animated:YES];
}

/**
 *  定义触发block调用的方法,此时需要将要传递的参数存入block中
 *  此处我将参数固定死了,开发中根据需要自己可以将需要的数值当做方法的参数,其实就是给方法添加参数即可,由外部决定参数值
 *  例如:-(void)TriggerBlock(name:String,age:Int) { }
 */
-(void)TriggerBlock{
    
    if (self.callBackBlock) {
        self.callBackBlock(@"夏远全",26);
    }
}

/**
 *  block触发调用后,对block属性赋值,同时提供调用外部访问block中数值的接口
 */
-(void)callBackBlockFunction:(OCBlock) block{
    self.callBackBlock = [block copy];
}


@end

SecondViewController.m

#import "SecondViewController.h"
#import "FirstViewController.h"

@interface SecondViewController ()
/**
 *  创建第一个控制器实例
 */
@property (strong,nonatomic)FirstViewController *firstVC;
@end

@implementation SecondViewController

-(void)viewDidLoad{
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor greenColor];
    
    
    _firstVC = [[FirstViewController alloc] init];
    
    /**
     * 接收block触发后回传的数值
     */
    [_firstVC callBackBlockFunction:^(NSString *name, NSInteger age) {
        NSLog(@"name:%@  age:%ld",name,age);
    }];
    
}

/**
 *  点击屏幕触发Block
 */
-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{
    
    [_firstVC TriggerBlock];
}

@end

点击演示结果如下,每一次点击都会触发闭包打印数据:

2017-01-06 17:51:19.814 闭包[26322:355426] name:夏远全  age:26
2017-01-06 17:51:27.837 闭包[26322:355426] name:夏远全  age:26
2017-01-06 17:51:28.037 闭包[26322:355426] name:夏远全  age:26
2017-01-06 17:51:28.221 闭包[26322:355426] name:夏远全  age:26
2017-01-06 17:51:28.405 闭包[26322:355426] name:夏远全  age:26
..............................................

 

本人原创,转载须注明出处,希望对大家有帮助,共同进步!!!

程序猿神奇的手,每时每刻,这双手都在改变着世界的交互方式!
posted @ 2017-01-06 17:55  XYQ全哥  阅读(7288)  评论(5编辑  收藏  举报