iOS值传递

前言

iOS传值方式很多，这里面我主要讲几种常用的传值；

以下传值正向传值A页面到B页面，反向传值B页面传到A页面。

1.属性传值

// A页面：

SecondViewController *svc = [[SecondViewController alloc]init];    
UINavigationController *nvc = [[UINavigationController alloc]initWithRootViewController:svc];    
svc.passValue = @"这是传的值";    
[self presentViewController:nvc animated:YES completion:nil];   

// B页面： 先声明一个属性：

@property (nonatomic,copy) NSString *passValue;    

使用传的值:

NSLog(@"%@",_passValue);  

2.NSUserDefaults传值

// A页面：

NSUserDefaults *ud = [NSUserDefaults standardUserDefaults];    
[ud setObject:@"这是传的值" forKey:@"passValue"];    
[ud synchronize];  

// B页面： 

NSUserDefaults *ud = [NSUserDefaults standardUserDefaults];    
NSString *str = [ud objectForKey:@"passValue"];    
NSLog(@"str == %@",str);  
 

3.delegate传值

// B页面设置代理

@protocol ChangeValueDelegate <NSObject>    
- (void)changeValueWithPassValue:(NSString *)passValue;    
@end    
    
@interface DetailViewController : UIViewController    
@property (assign, nonatomic) id<ChangeValueDelegate> delegate;    
@end  

// 赋值

if ([self.delegate respondsToSelector:@selector(changeValueWithPassValue:)]) {    
            [self.delegate changeValueWithPassValue:@"这是传的值"];    
}  

/****************************************************/

// A页面遵循代理

@interface RootViewController ()<ChangeValueDelegate>  

SecondViewController *dvc = [[SecondViewController alloc] init];    
dvc.delegate = self;    
[self.navigationController pushViewController:dvc animated:YES];  

// 实现代理

- (void)changeValueWithPassValue:(NSString *)titleStr{    
    NSLog(@"titleStr == %@",titleStr);    
}  

4.NSNotificationCenter传值

// A页面发送通知

NSDictionary *dict = [NSDictionary dictionaryWithObject:@"我是传的值" forKey:@"value"];    
[[NSNotificationCenter defaultCenter] postNotificationName:@"KPassVaule" object:nil userInfo:dict];     
    
// B页面接收通知

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(getPassVauleget:) name:@"KPassVaule" object:nil];  

- (void)getPassVauleget:(NSNotification *)notifi{    
    NSString *str = [notifi.userInfo objectForKey:@"value"];    
    NSLog(@"str == %@",str);    
}  

5.KVO传值

// 在初始化方法中加入

[_stu addObserver:self forKeyPath:@"name" options:NSKeyValueObservingOptionNew | NSKeyValueObservingOptionOld context:nil];    
    
// 在dealloc中移除KVO监听：

[_stu removeObserver:self forKeyPath:@"name" context:nil];    

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(voidvoid *)context{    
    if ([object isKindOfClass:[Student class]]) {    
        NSLog(@"_stu-old:%@",[change objectForKey:@"old"]);    
        NSLog(@"_stu-new:%@",[change objectForKey:@"new"]);    
    }    
}  

6.blcok反向传值

// A页面

DetailViewController *dvc = [[DetailViewController alloc] init];    
dvc.fontSize = _label.font.pointSize;    
void (^mBlocks)(float value);    
mBlocks = ^(float value){    
     _label.font = [UIFont systemFontOfSize:value];    
};    
[dvc changeFont:mBlocks];    
[self presentViewController:dvc animated:YES completion:^{    
   NSLog(@"hb");    
}]; 

// B页面

#import <UIKit/UIKit.h>    
    
@interface DetailViewController : UIViewController{    
    void (^_mBlock)(float value);    
}    
    
@property (assign, nonatomic) float fontSize;    
    
- (void)changeFont:(void (^)(float value))mBlock;    
    
@end 

// 传值

_mBlock(1111.00);