效果：viewController里面放置一个按钮和Lab，点击按钮进入oneViewController（delegate回调）或者BlockViewController（block回调），两者控制器里面分别有一个输入框，输入文字后 点击完成，把文本框输入的内容回调到 VIewController里面的 Lab上显示出来!
第一种：delegate回调
1.首先在oneViewController.h里面声明代理
#import <UIKit/UIKit.h>
//协议
@protocol OneViewDelegate
//代理方法
-(void)returnFieldText:(NSString*)string;
@end
@interface OneViewController : UIViewController
//声明属性
@property(nonatomic,strong)id <OneViewDelegate>delegate;
@end
2.实现代理
#import "OneViewController.h"
@interface OneViewController ()
@property(nonatomic,strong)UITextField *textField;
@end
@implementation OneViewController
- (void)viewDidLoad {
[super viewDidLoad];
self.view.backgroundColor=[UIColor whiteColor];
self.textField = [[UITextField alloc] initWithFrame:CGRectMake(100, 100, 100, 30)];
self.textField.backgroundColor = [UIColor greenColor];
[self.view addSubview:self.textField];
UIBarButtonItem *rightButton = [[UIBarButtonItem alloc] initWithTitle:@"完成" style:UIBarButtonItemStylePlain target:self action:@selector(doRightButtonAction)];
self.navigationItem.rightBarButtonItem = rightButton;
}
-(void)doRightButtonAction{
NSLog(@"这是第二步");
[self.delegate returnFieldText:self.textField.text];
[self.navigationController popViewControllerAnimated:YES];
}
3. 在ViewController回调
#import "ViewController.h"
#import "OneViewController.h"
@interface ViewController ()<BlockViewDelegate>
@property(nonatomic,strong)UILabel *lab;
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
self.view.backgroundColor=[UIColor whiteColor];
UIButton *btn=[UIButton buttonWithType:UIButtonTypeCustom];
btn.frame=CGRectMake(0, 0, [UIScreen mainScreen].bounds.size.width, [UIScreen mainScreen].bounds.size.height);
[btn addTarget:self action:@selector(back) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:btn];
self.lab=[[UILabel alloc]initWithFrame:CGRectMake(0, 80, 200, 50)];
self.lab.backgroundColor=[UIColor redColor];
[self.view addSubview:self.lab];
}
-(void)back{
OneViewController *one=[[OneViewController alloc]init];
one.delegate = self; （注意：控制器入栈，这个必须写）
[self.navigationController pushViewController:one animated:YES];
}
//代理回调
-(void)returnFieldText:(NSString *)string{
NSLog(@"这是第3");
[self.lab setText:string];
}
第二种 Block回调
1.声明block
#import <UIKit/UIKit.h>
//声明别名ReturnTextWithBlock
typedef void (^ReturnTextWithBlock)(NSString *text);
@interface BlockViewController : UIViewController
//属性
（注意：block修饰必须用copy，不然会出问题）
@property(nonatomic,copy)ReturnTextWithBlock returnTextBlock;
//方法
-(void)returnTextFieldWithBlock:(ReturnTextWithBlock)block;
@end
2.实现ReturnTextWithBlock
#import "BlockViewController.h"
@interface BlockViewController ()
@property(nonatomic,strong)UITextField *textField;
@end
@implementation BlockViewController
- (void)viewDidLoad {
[super viewDidLoad];
self.view.backgroundColor=[UIColor whiteColor];
self.textField = [[UITextField alloc] initWithFrame:CGRectMake(100, 100, 100, 30)];
self.textField.backgroundColor = [UIColor greenColor];
[self.view addSubview:self.textField];
UIBarButtonItem *rightButton = [[UIBarButtonItem alloc] initWithTitle:@"完成" style:UIBarButtonItemStylePlain target:self action:@selector(doRightButtonAction)];
self.navigationItem.rightBarButtonItem = rightButton;
}
-(void)doRightButtonAction{
NSLog(@"第2");
self.returnTextBlock(self.textField.text);
[self.navigationController popViewControllerAnimated:YES];
}
-(void)returnTextFieldWithBlock:(ReturnTextWithBlock)block{
NSLog(@"第1");
block是存在栈区的，随着viewDidLoad消失会消失，我们要操作 将它放入堆区，赋值 引用计数加1 ，不会导致中途丢失
self.returnTextBlock = block;
}
3.回调实现block
#import "ViewController.h"
#import "BlockViewController.h"
@interface ViewController ()
@property(nonatomic,strong)UILabel *lab;
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
self.view.backgroundColor=[UIColor whiteColor];
UIButton *btn=[UIButton buttonWithType:UIButtonTypeCustom];
btn.frame=CGRectMake(0, 0, [UIScreen mainScreen].bounds.size.width, [UIScreen mainScreen].bounds.size.height);
[btn addTarget:self action:@selector(back) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:btn];
self.lab=[[UILabel alloc]initWithFrame:CGRectMake(0, 80, 200, 50)];
self.lab.backgroundColor=[UIColor redColor];
[self.view addSubview:self.lab];
}
-(void)back{
BlockViewController *BlockVC=[[BlockViewController alloc]init];
__weak typeof (self)weakSelf = self;
//回调block
[BlockVC returnTextFieldWithBlock:^(NSString *text) {
[weakSelf.lab setText:text];
}];
[self.navigationController pushViewController:BlockVC animated:YES];
}
@end
传值的话：还有属性，通知等传值方式
