委托

1.委托 的作用  ：回传值（回调）；

2.当我们声明遵循了协议的属性时，属性的关键字weak或assign   weak，assign 的作用是 避免循环引用

3.委托的特点：一对一

4.用途是用在有上下级关系的两个view(类），不能跨级调用。（即a-b时需要在b中添加一个协议 在a中初始化b,用self,

创建：

1.//在被委托者的声明文件(.h)中进行协议的声明，然后创建遵循协议的属性，如上2所示

#import <Foundation/Foundation.h>

@protocol PaymentDelegate <NSObject>

-(void)payment:(float)money;

@end

@interface Mediation : NSObject

@property (nonatomic, weak) id <PaymentDelegate> delegate;

-(void)handle;

@end

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#import "Mediation.h"

@implementation Mediation

-(void)handle{
    NSLog(@"找到房源，请给钱");
   
    [_delegate payment:10.0];
}

@end

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//发布委托  作用：委托谁帮我做事（调用协议方法）

#import "Buyer.h"

@implementation Buyer

-(void)findMediation{
    NSLog(@"我需要房源");
   
    Mediation *m = [[Mediation alloc] init];
    m.delegate = self;
    [m handle];

}

-(void)payment:(float)money{
    NSLog(@"付钱:%.2f",money);
}

@end

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#import <Foundation/Foundation.h>
#import "Mediation.h"

@interface Buyer : NSObject<PaymentDelegate>

-(void)findMediation;

@end

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1。回传值 的调用

传什么内容就要用什么类型的值接收例 

//传值：
-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath{

    detailViewController *detaqil =[[detailViewController alloc]init];

    detaqil.delegate = self;

   

    detaqil.perrr =arr[indexPath.row];//关键的地方传值的类型 此时的perrr相当于数组的一个对象，取值的话用perrr.数组的内容

    sedter=indexPath.row;
        [self.navigationController pushViewController:detaqil animated:YES];
   
    [tableView deselectRowAtIndexPath:indexPath animated:YES];

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 self.view.backgroundColor = [UIColor whiteColor];
   
    nametext = [[UITextField alloc]initWithFrame:CGRectMake(50, 100, 200, 50)];
    nametext.borderStyle =UITextBorderStyleRoundedRect;

    nametext.backgroundColor = [UIColor whiteColor];

    nametext.text =_perrr.name;//(perrr.name 相当于单一数组中的元素之一

   
   nametext.userInteractionEnabled =NO;
    [self.view addSubview:nametext];

   

//是否允许编辑
-(BOOL)tableView:(UITableView *)tableView canEditRowAtIndexPath:(NSIndexPath *)indexPath{
   
    return YES;
}
//删行
-(void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath{
    [arr removeObjectAtIndex:indexPath.row];
    [tableView deleteRowsAtIndexPaths:@[indexPath] withRowAnimation:0];
   
   
}
-(void)ediddd:(NSString *)name andimage:(NSString *)phone{
    Person *prr =[[Person alloc]init];
    prr.name =name;
    prr.phone =phone;
    [arr replaceObjectAtIndex:sedter withObject:prr];
    [table reloadData];
   
   
}

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//增加值
-(void)addindex{
   
    AddViewController *addview =[[AddViewController alloc]init];
    addview.delegate =self;
   
    [self.navigationController pushViewController:addview animated:YES];
   
   
}

-(void)addcontrioldelegate:(NSString *)name andphone:(NSString *)phone{
    Person *peerr = [[Person alloc]init];
    peerr.name =name;
    peerr.phone =phone;
    [arr addObject:peerr];
    [table reloadData];
 

}

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9.委托用于自定义控件

//委托用于自定义控件
#import "ViewController.h"
#import "MyView.h"
@interface ViewController ()<BtnPressedDelegate>
@end
@implementation ViewController
- (void)viewDidLoad {
    [super viewDidLoad];

    MyView *myView = [[MyView alloc] initWithFrame:CGRectMake(40, 80, 200, 200)];
    myView.delegate = self;
    [self.view addSubview:myView];
}
-(void)btnPressed{
    self.view.backgroundColor = [UIColor grayColor];
}
- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> #import <UIKit/UIKit.h>
@protocol BtnPressedDelegate <NSObject>
-(void)btnPressed;
@end
@interface MyView : UIView
@property (nonatomic, weak) id<BtnPressedDelegate> delegate;

@end>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> #import "MyView.h"
@implementation MyView
-(instancetype)initWithFrame:(CGRect)frame{
    self = [super initWithFrame:frame];
    if (self) {
       
        self.backgroundColor = [UIColor brownColor];
        self.layer.cornerRadius = 5;
        self.layer.masksToBounds = YES;
       
        UIButton *btn = [UIButton buttonWithType:UIButtonTypeCustom];
       
        btn.frame = CGRectMake(20, 40, 80, 80);
        [btn setTitle:@"按钮" forState:UIControlStateNormal];
        [btn setTitleColor:[UIColor whiteColor] forState:UIControlStateNormal];
        [btn addTarget:self action:@selector(btnPressed) forControlEvents:UIControlEventTouchUpInside];
        [self addSubview:btn];
          }
    return self;
}
-(void)btnPressed{
    NSLog(@"按钮被点击");
   
    [_delegate btnPressed];
}

@end