1 通知的使用
适合没有关联的对象之间的传值和一对多情况的传值
1.通知发送者发布通知
[[NSNotificationCenter defaultCenter] postNotificationName:@"plusClickNotification" object:self];
[[NSNotificationCenter defaultCenter] postNotificationName:@"minusClickNotification" object:self];
2.通知观察者注册并接收通知
// 监听通知
NSNotificationCenter *center = [NSNotificationCenter defaultCenter];
[center addObserver:self selector:@selector(plusClick:) name:@"plusClickNotification" object:nil];
[center addObserver:self selector:@selector(minusClick:) name:@"minusClickNotification" object:nil];
- (void)dealloc{
// 移除通知
[[NSNotificationCenter defaultCenter] removeObserver:self];
}
#pragma mark - 通知的监听方法
- (void)plusClick:(NSNotification *)note
{
// 通知的发布者
WineCell *cell = note.object;
// 计算总价
int totalPrice = self.totalPriceLabel.text.intValue + cell.wine.money.intValue;
// 设置总价
self.totalPriceLabel.text = [NSString stringWithFormat:@"%d",totalPrice];
}
- (void)minusClick:(NSNotification *)note
{
// 通知的发布者
WineCell *cell = note.object;
// 计算总价
int totalPrice = self.totalPriceLabel.text.intValue - cell.wine.money.intValue;
// 设置总价
self.totalPriceLabel.text = [NSString stringWithFormat:@"%d",totalPrice];
}
2 代理
适合一对一情况的、并且有关联的对象之间的传值，代码略微分散
1.定义代理协议和代理属性
// 定义代理协议
@protocol WineCellDelegate <NSObject>
@optional
- (void)wineCellDidClickPlusBtn:(WineCell *)wineCell;
- (void)wineCellDidClickMinusBtn:(WineCell *)wineCell;
@end
// 代理属性
@property (nonatomic, weak) id<WineCellDelegate> delegate;
2.调用代理方法时先做判断
// 通知代理,调用代理方法
// 判断能否调用代理方法
if ([self.delegate respondsToSelector:@selector(wineCellDidClickPlusBtn:)]) {
// 调用代理方法
[self.delegate wineCellDidClickPlusBtn:self];
}
if([self.delegate respondsToSelector:@selector(wineCellDidClickMinusBtn:)]){
[self.delegate wineCellDidClickMinusBtn:self];
}
3.遵守代理协议,成为代理,实现代理方法
// 遵守代理协议
@interface ViewController ()<WineCellDelegate>
// 成为代理
cell.delegate = self;
#pragma mark - 实现代理方法
- (void)wineCellDidClickPlusBtn:(WineCell *)wineCell {
// 计算总价
int totalPrice = self.totalPriceLable.text.intValue + wineCell.wineItem.money.intValue;
// 设置总价
self.totalPriceLable.text = [NSString stringWithFormat:@"%d",totalPrice];
self.buyBtn.enabled = YES;
if (![self.shopsArray containsObject:wineCell.wineItem]) {
[self.shopsArray addObject:wineCell.wineItem];
}
}
-(void)wineCellDidClickMinusBtn:(WineCell *)wineCell {
// 计算总价
int totalPrice = self.totalPriceLable.text.intValue - wineCell.wineItem.money.intValue;
// 设置总价
self.totalPriceLable.text = [NSString stringWithFormat:@"%d",totalPrice];
self.buyBtn.enabled = totalPrice > 0;
// 移除用户不再购买的商品
if (wineCell.wineItem.count == 0) {
[self.shopsArray removeObject:wineCell.wineItem];
}
}
3 block传值
适合一对一情况的、并且有关联的对象之间的传值，代码比较集中。
参考文章：http://www.jianshu.com/p/7d729fc351c8
传值方：
//.h 文件
/**
* 类型自定义
*/
typedef void (^ReturnValueBlock) (NSString *strValue);
@interface NextViewController : UIViewController
/**
* 声明一个ReturnValueBlock属性，这个Block是获取传值的界面传进来的
*/
@property(nonatomic, copy) ReturnValueBlock returnValueBlock;
@end
=================================================================
//.m 文件
#import "NextViewController.h"
@interface NextViewController ()
@property (weak, nonatomic) IBOutlet UITextField *inputText;
- (IBAction)back:(id)sender;
@end
@implementation NextViewController
- (void)viewDidLoad {
[super viewDidLoad];
self.navigationItem.title = @"第二个界面";
}
/**
* 返回上一个界面
*
* @param sender 按钮
*/
- (IBAction)back:(id)sender {
NSString *inputString = self.inputText.text;
if (self.returnValueBlock) {
//将自己的值传出去，完成传值
self.returnValueBlock(inputString);
}
[self.navigationController popViewControllerAnimated:YES];
}
@end
捕获方：
//.m 文件
#import "ViewController.h"
#import "NextViewController.h"
@interface ViewController ()
@property (weak, nonatomic) IBOutlet UILabel *nextPassedValue;
- (IBAction)next:(id)sender;
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
}
//点击按钮跳转到第二个界面
- (IBAction)next:(id)sender {
NextViewController *nvc = [[NextViewController alloc]init];
//赋值Block，并将捕获的值赋值给UILabel
nvc.returnValueBlock = ^(NSString *passedValue){
self.nextPassedValue.text = passedValue;
};
[self.navigationController pushViewController:nvc animated:YES];
}
@end
传值方式可参考的文章：
http://www.jianshu.com/p/51153323c8bf
