target-action设计模式-优快云博客

本文介绍如何在iOS应用中利用target-action设计模式将事件处理分离到控制器层，实现动态事件响应。通过定义目标（target）和动作（action），开发者可以在不同实例上执行不同方法，增强应用的灵活性和可维护性。具体实现包括定义TouchView类，设置目标和动作属性，并在RootViewController中实现动态事件处理逻辑。

target-action是模仿系统的button。即将事件的处理交给外界，不在自己内部写死。

target-action设计模式主要涉及到两方面的内容

target：目标

action：动作

target-action可以让不同的实例对象在相同的时间点执行不同的方法，从而达到不同的效果

target-action设计模式存在的意义即将事件分离，View只负责显示，具体的事件处理交给controller。是MVC中View层和Controller层通信的一种方式。

#import <UIKit/UIKit.h>

@interface TouchView : UIView

#warning 1.给外界提供目标和动作属性，让外界可以设置。
@property(nonatomic, retain)id tagret; // 目标
@property(nonatomic, assign)SEL action; // 动作

@end

#import "TouchView.h"

@implementation TouchView
#warning 2.重写dealloc方法 释放对应的实例变量
- (void)dealloc
{
    [_tagret release];
    [super dealloc];
}

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
#warning 4.在某个时间点让目标去执行对应的方法
    [_tagret performSelector:_action withObject:self];
}

#import "RootViewController.h"
#import "TouchView.h"

@interface RootViewController ()

@end

@implementation RootViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    
    TouchView *colorView = [[TouchView alloc] initWithFrame:CGRectMake(130, 50, 100, 100)];
    colorView.backgroundColor = [UIColor redColor];

#warning 3.在外界设置target、action。
    colorView.tagret = self; 
    colorView.action = @selector(changeColor:);
    [self.view addSubview:colorView];
    [colorView release];
    
    TouchView *positionView = [[TouchView alloc] initWithFrame:CGRectMake(130, 250, 100, 100)];
    positionView.backgroundColor = [UIColor greenColor];
    positionView.tagret = self;
    positionView.action = @selector(changePosition:);
    [self.view addSubview:positionView];
    [positionView release];
    
    TouchView *sizeView = [[TouchView alloc] initWithFrame:CGRectMake(130, 450, 100, 100)];
    sizeView.backgroundColor = [UIColor blueColor];
    sizeView.tagret = self;
    sizeView.action = @selector(changeSize:);
    [self.view addSubview:sizeView];
    [sizeView release];
    
}

#warning 5.实现action方法，方法按需求实现
- (void)changeColor:(TouchView *)touchView
{
    touchView.backgroundColor = [UIColor colorWithRed:(arc4random() % 256 / 255.0) green:(arc4random() % 256 / 255.0) blue:(arc4random() % 256 / 255.0) alpha:1];
}

- (void)changePosition:(TouchView *)touchView
{
    CGFloat minX = 0;
    CGFloat maxX = [[UIScreen mainScreen] bounds].size.width;
    CGFloat x = arc4random() % (int)(maxX - minX + 1) + minX;
    
    CGFloat minY = 0;
    CGFloat maxY = [[UIScreen mainScreen] bounds].size.height;
    CGFloat y = arc4random() % (int)(maxY - minY + 1) + minY;
    
    touchView.center = CGPointMake(x, y);
}

- (void)changeSize:(TouchView *)touchView
{
    CGFloat minWidth = 38;
    CGFloat maxWidth = [[UIScreen mainScreen] bounds].size.width;
    CGFloat width = arc4random() % (int)(maxWidth - minWidth + 1) + minWidth;
    
    CGFloat minHeight = 38;
    CGFloat maxHeight = [[UIScreen mainScreen] bounds].size.height;
    CGFloat height = arc4random() % (int)(maxHeight - minHeight + 1) + minHeight;
    
    touchView.bounds = CGRectMake(0, 0, width, height);
}

转载于:https://www.cnblogs.com/sqdhy-zq/p/4764467.html