关于iOS往回传值的函数，比较基础也比较常用的三个——代理、通知、block块传值。
本文使用了四个控制器，一个是导航控制器。为了简单化，使用storyboard拖线push方式切换控制器。也为了偷懒一个项目展示三种回传值方式：
storyboard.png
RZNextViewController.h
//第二个控制器的.h文件
#import <UIKit/UIKit.h>
@class RZNextViewController;
@protocol RZNextViewControllerDelegate <NSObject>
@optional
- (void)nextViewController:(RZNextViewController *)nextViewController withTitle:(NSString *)title;
@end
@interface RZNextViewController : UIViewController
@property (nonatomic,weak) id<RZNextViewControllerDelegate>delegate;
@property (copy, nonatomic) void (^strBlock)(NSString*);
@end
RZNextViewController.m
//第二个控制器的.m文件
#import "RZNextViewController.h"
@interface RZNextViewController ()
@property (weak, nonatomic) IBOutlet UITextField *textField;//代理传值文本框
@property (weak, nonatomic) IBOutlet UITextField *textField1;//通知传值文本框
@property (weak, nonatomic) IBOutlet UITextField *textField2;//block传值文本框
@end
@implementation RZNextViewController
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view.
}
//代理回调按钮点击
- (IBAction)backButtonClick:(id)sender {
NSString *backTitle = self.textField.text;
if ([self.delegate respondsToSelector:@selector(nextViewController:withTitle:)]) {
[self.delegate nextViewController:self withTitle:backTitle];
}
[self.navigationController popToRootViewControllerAnimated:YES];
}
//通知回调按钮点击
- (IBAction)back1ButtonClick:(id)sender {
NSNotificationCenter *noCenter = [NSNotificationCenter defaultCenter];
[noCenter postNotificationName:@"huidiao" object:self.textField1.text];
[self.navigationController popToRootViewControllerAnimated:YES];
}
//block块回调按钮点击
- (IBAction)blockButtonClick:(id)sender {
if (self.strBlock) {
self.strBlock(self.textField2.text);
}
[self.navigationController popViewControllerAnimated:YES];
}
@end
接着是重点了，在根控制器中分别实现三种方式回传时赋值操作。
其中block块赋值方式虽然写在，push调用的方法中，在block块传值的第二个页面控制器回调时，程序会直接跳入- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender 方法内部，直接执行赋值的部分。
#import "ViewController.h"
#import "RZNextViewController.h"
@interface ViewController ()<RZNextViewControllerDelegate>
//显示回传值的文本框
@property (weak, nonatomic) IBOutlet UILabel *textLabel;
@end
@implementation ViewController
//push时调用该方法
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender{
RZNextViewController *nextVC = segue.destinationViewController;
nextVC.delegate = self;
//block块回传时，赋值调用
nextVC.strBlock = ^(NSString *text){
self.textLabel.text = text;
};
}
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
NSNotificationCenter *noCenter = [NSNotificationCenter defaultCenter];
[noCenter addObserver:self selector:@selector(show:) name:@"huidiao" object:nil];
}
- (void)show:(NSNotification *)notification{
NSString *str = notification.object;
self.textLabel.text = str;
}
//实现代理方法
- (void)nextViewController:(RZNextViewController *)nextViewController withTitle:(NSString *)title{
self.textLabel.text = title;
}
