参考地址 IOS:两种回调的方式实现(delegate和block)
通过block回调，可以轻松实现类似android的 setListener这样的机制，记得使用弱引用哦
我要实现的效果：在ViewController里有一个Button,点击button进入BlockView。在BlockView有一个TextField,输入文字后点击完成，可以把textField里的文字回调到ViewController的Button上显示。
第一种：delegate回调
回调类ViewController.m：#import "ViewController.h"
#import "BlockView.h"
@interface ViewController ()<BlockViewDelegate>
@property (strong, nonatomic) UIButton *myButton;
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
self.view.backgroundColor = [UIColor whiteColor];
self.myButton = [[UIButton alloc] initWithFrame:CGRectMake(100, 100, 60, 30)];
self.myButton.backgroundColor = [UIColor redColor];
[self.myButton addTarget:self action:@selector(doButtonAction) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:self.myButton];
}
- (void)doButtonAction{
BlockView *blockView = [[BlockView alloc] init];
blockView.delegate = self;
[self.navigationController pushViewController:blockView animated:YES];
}
- (void)returnFieldText:(NSString *)string{
[self.myButton setTitle:string forState:UIControlStateNormal];
}
调用类BlockView.h
#import <UIKit/UIKit.h>
@protocol BlockViewDelegate
- (void)returnFieldText:(NSString *)string;
@end
@interface BlockView : UIViewController
@property (assign,nonatomic) id<BlockViewDelegate> delegate;
@end
调用类BlockView.m
#import "BlockView.h"
@interface BlockView ()
@property (strong, nonatomic) UITextField *textField;
@end
@implementation BlockView
- (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{
[self.delegate returnFieldText:self.textField.text];
[self.navigationController popViewControllerAnimated:YES];
}
第二种：block回调
回调类ViewController.m:
#import "ViewController.h"
#import "BlockView.h"
@interface ViewController ()
@property (strong, nonatomic) UIButton *myButton;
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
self.view.backgroundColor = [UIColor whiteColor];
self.myButton = [[UIButton alloc] initWithFrame:CGRectMake(100, 100, 60, 30)];
self.myButton.backgroundColor = [UIColor redColor];
[self.myButton addTarget:self action:@selector(doButtonAction) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:self.myButton];
}
- (void)doButtonAction{
BlockView *blockView = [[BlockView alloc] init];
__weak typeof (self)weakSelf = self;
//回调block
[blockView returnTextFieldWithBlock:^(NSString *text) {
[weakSelf.myButton setTitle:text forState:UIControlStateNormal];
}];
[self.navigationController pushViewController:blockView animated:YES];
}调用类BlockView.h
#import <UIKit/UIKit.h>
typedef void (^ReturnTextWithBlock)(NSString *text);
@interface BlockView : UIViewController
@property (copy ,nonatomic) ReturnTextWithBlock returnTextWithBlock;
- (void)returnTextFieldWithBlock:(ReturnTextWithBlock)block;
@end
调用类BlockView.m
#import "BlockView.h"
@interface BlockView ()
@property (strong, nonatomic) UITextField *textField;
@end
@implementation BlockView
- (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{
self.returnTextWithBlock(self.textField.text);
[self.navigationController popViewControllerAnimated:YES];
}
- (void)returnTextFieldWithBlock:(ReturnTextWithBlock)block{
self.returnTextWithBlock = block;
}