delegate和targetAction.docxVIP

delegate和targetAction的异同target...action和delegate的作用都是解耦,降低程序的耦合性.target...action通常用于单个事件(类似button)和完成某一任务,而delegate通常用于监控一系列事件(类似textField).?target...action内部实现为[target performSelector:actionwithObject:self],继承于Object.在.h文件里声明属性target和action用于保存目标,delegate在.h里声明一个协议,协议名为类名加Delegate,协议里方法至少要有一个参数,参数类型为控件类型.?target...action在外部使用给内部的target,action赋值,可以单独赋值,也可以一起赋值,实现action方法.delegate在外部使用也是给delegate赋值,实现协议中的方法.1.代理(delegate)传值 ---- 顾名思义就是委托别人办事，就是当一件事情发生后，自己不处理，让别人来处理。?? 实质就是：比如右AB两个页面，A想要传值给B ，就只要先在A中得到B的指针，然后将想要传的值赋给B，之后跳转代码如下:A.h @protocol HMTShowViewControllerDelegate NSObject @optional - (void)showViewGiveValue:(NSString *)text; @end @interface HMTShowViewController : UIViewController UITextFieldDelegate @property (nonatomic,copy)NSString * text; // 定义一个代理 @property (nonatomic,assign)idHMTShowViewControllerDelegate delegate; @end A.m - (void)popPerView:(UIBarButtonItem *)barButton{ // 在页面跳转前将参数传出去 if ([self.delegaterespondsToSelector:@selector(showViewGiveValue:)]) { [self.delegateshowViewGiveValue:_showTextField.text]; } [self.navigationControllerpopViewControllerAnimated:YES]; } B.h @interface HMTInputViewController : UIViewController HMTShowViewControllerDelegate B.m - (void)pushNextViewControl:(UIBarButtonItem *)button{ HMTShowViewController * showVC = [[HMTShowViewControlleralloc]init]; showVC.text = _textField.text; // 将代理对象设置成B showVC.delegate = self; [self.navigationControllerpushViewController:showVCanimated:YES]; [showVC release]; } // B实现协议里面的方法 - (void)showViewGiveValue:(NSString *)text{ _inputLabel.text = text; }2.单例传值 ------- 如果页面之间相隔很多,要进行传值,将值保存到第三方,将第三方设置为单例模式??代码如下:static HMTInputViewController * shareRootViewController = nil; @implementation HMTInputViewController +(HMTInputViewController *)sharedController{ @synchronized(self){ if(shareRootViewController == nil){ shareRootViewController = [[self alloc] init] ; } } return shareRootViewC