UI target/action设计模式

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target/action设计模式

MyView.h

@interface MyView : UIView{    //保存对象    id _target;    //保存方法    SEL _action;}//给实例变量_target,_action赋值- (void)addTarget:(id)target action:(SEL)action;<p style="margin-top: 0px; margin-bottom: 0px; font-size: 18px; font-family: Menlo;"><pre name="code" class="objc">@property(nonatomic,retain) UIView *greenView;

@end

MyView.m

<pre name="code" class="objc">@implementation MyView- (void)dealloc{    [_greenView release];    [super dealloc];}- (id)initWithFrame:(CGRect)frame{    self = [super initWithFrame:frame];    if (self) {        UIView *greenView=[[UIView alloc]initWithFrame:CGRectMake(40, 120, 100, 100)];        greenView.backgroundColor=[UIColor greenColor];        [self addSubview:greenView];        [greenView release];        self.greenView=greenView;    }    return self;}//给实例变量_target,_action赋值- (void)addTarget:(id)target action:(SEL)action{    _target=target;    _action=action;}-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event{    //让_target对象执行_action方法，参数是nil    [_target performSelector:_action withObject:self.greenView];}@end

RootViewController.m

@implementation RootViewController-(void)loadView{    //在loadView中给self.view赋值，没有赋值之前self.view是空的。如果不重写loadView方法，则默认创建一个空白的view    MyView *myView=[[MyView alloc]initWithFrame:CGRectMake(0, 0, 320, 480)];    myView.backgroundColor=[UIColor cyanColor];    [myView addTarget:self action:@selector(changeColor:)];    self.view=myView;    [myView release];}- (void)changeColor:(UIView*)aView{    //改变颜色    float red=arc4random()%256/255.0;    float green=arc4random()%256/255.0;    float blue=arc4random()%256/255.0;    UIColor *randColor=[UIColor colorWithRed:red green:green blue:blue alpha:1];    aView.backgroundColor=randColor;}@end

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