导航控制器下UIViewController之间的传值 ------ 代理(delegate)传值 单例传值 Target-Action传值 属性传值 block传值 通知传值
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)id<HMTShowViewControllerDelegate> delegate;
@end
A.m
- (void)popPerView:(UIBarButtonItem *)barButton{
// 在页面跳转前将参数传出去
if ([self.delegate respondsToSelector:@selector(showViewGiveValue:)]) {
[self.delegate showViewGiveValue:_showTextField.text];
}
[self.navigationController popViewControllerAnimated:YES];
}
B.h
@interface HMTInputViewController : UIViewController <HMTShowViewControllerDelegate>
B.m
- (void)pushNextViewControl:(UIBarButtonItem *)button{
HMTShowViewController * showVC = [[HMTShowViewController alloc]init];
showVC.text = _textField.text;
// 将代理对象设置成B
showVC.delegate = self;
[self.navigationController pushViewController:showVC animated: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 shareRootViewController;
}
要将HMTInputViewController中的一个UITextField编辑的内容传到HMTShowViewController中的UILabel
_showLabel.text = [HMTInputViewController sharedController].textField.text;
3.Target-Action传值
实质就是：A页面要给B页面传值,A就提供接口出去,抓A到B内部来,A间接调用自己内部方法(相当于,A把自己内部需 要操作的方法,传到B内来,到B内部进行赋值,这样就不存在访问不到各自的局部实例变量)
@property (nonatomic,assign)id traget; @property (nonatomic,assign)SEL action;
[self.traget performSelector:self.action withObject:nil];(是否需要传参数自己定,最多2个)
代码如下:
A.h
@interface HMTShowViewController : UIViewController <UITextFieldDelegate>
@property (nonatomic,assign) id traget;
@property (nonatomic,assign) SEL action;
@end
A.m
- (void)popPerView:(UIBarButtonItem *)barButton{
[self.traget performSelector:self.action withObject:_showTextField.text];
[self.navigationController popViewControllerAnimated:YES];
}
B.m
- (void)pushNextViewControl:(UIBarButtonItem *)button{
HMTShowViewController * showVC = [[HMTShowViewController alloc]init];
showVC.traget = self;
showVC.action = @selector(changeLabelText:);
[self.navigationController pushViewController:showVC animated:YES];
}
- (void)changeLabelText:(NSString *)text{
_inputLabel.text = text;
}
4.属性/方法传值
A - pushViewController - B 在A视图中有B视图的对象 ,可直接操作
- (void)didClickRightButtonItemAction
{
InputViewController * inputVC = [[InputViewController alloc] init];
[self.navigationController pushViewController:inputVC animated:YES];
[inputVC release];
}
B - popViewControllerAnimated - A 因为A推出B,A只是隐藏了,退到栈底去了,在B返回A,A的viewDidLoad并不会再次调用
- (void)didClickLeftButtonItemAction
{
ShowViewController * showView = (ShowViewController *)[self.navigationController.viewControllers objectAtIndex:0];
[self.navigationController popViewControllerAnimated:YES];
}
5.block传值(A-view 传值给 B-view)
@释放 Block_release(_doTransferMsg);
A.h
@property (nonatomic,copy) void(^doTransferMsg)(NSString * msg);
A.m
- (void)popPerView:(UIBarButtonItem *)barButton{
if (_doTransferMsg) {
_doTransferMsg(_showTextField.text);
}
[self.navigationController popViewControllerAnimated:YES];
}
B.m
- (void)pushNextViewControl:(UIBarButtonItem *)button{
HMTShowViewController * showVC = [[HMTShowViewController alloc]init];
// block传值
[showVC setDoTransferMsg:^(NSString * msg) {
dispatch_async(dispatch_get_main_queue(), ^{
_inputLabel.text = msg; });
}];
[self.navigationController pushViewController:showVC animated:YES];
[showVC release];
}
6.通知传值(同上,也是A传给B)
A.m
- (void)popPerView:(UIBarButtonItem *)barButton{
[[NSNotificationCenter defaultCenter] postNotificationName:@"changeLabelTextNotification" object:_showTextField.text];
[self.navigationController popViewControllerAnimated:YES];
}
B.m
- (void)viewDidLoad
{
[super viewDidLoad];
// 通知中心,发送一条消息传值--------其中name千万不要写错了,会出现在3个地方
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(showViewGiveValue:) name:@"changeLabelTextNotification" object:nil];
}
- (void)showViewGiveValue:(NSNotification *)notification{
// 取出notification的object
id text = notification.object;
_inputLabel.text = text;
}
-(void)dealloc{
// 消息发送完,要移除掉
[[NSNotificationCenter defaultCenter] removeObserver:self name:@"changeLabelTextNotification" object:nil];
[super dealloc];
}