iOS中使用block传值

转自：http://blog.sina.com.cn/s/blog_60b45f230100yiaf.html

用此方法传值可以替代委托了。具体例子：

MainView.h

#import <UIKit/UIKit.h>



@interface MainView : UIViewController

{

    IBOutlet UIButton* btn;

    IBOutlet UILabel* labShow;

}

-(IBAction)push:(id)sender;

@end

 

MainView.m

#import "MainView.h"

#import "SecondView.h"



@implementation MainView



- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil

{

    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];

    if (self) {

    }

    return self;

}



- (void)didReceiveMemoryWarning

{

    [super didReceiveMemoryWarning];

}



#pragma mark - View lifecycle



- (void)viewDidLoad

{

    [super viewDidLoad];

}

-(IBAction)push:(id)sender

{

    SecondView *s = [[SecondView alloc] initwithBlock:^(NSString *str){

        NSLog(@"%@",str);

        labShow.text = str;

    }];

    [self.navigationController pushViewController:s  animated:YES];

    [s release];

}

- (void)viewDidUnload

{

    [super viewDidUnload];

}



- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation

{

    return (interfaceOrientation == UIInterfaceOrientationPortrait);

}



@end

 

SecondView.h

#import <UIKit/UIKit.h>

typedef void (^MyBlock)(NSString *);



@interface SecondView : UIViewController

{

    IBOutlet UITextField* txtView;

    MyBlock my;

}

-(IBAction)back:(id)sender;

-(id)initwithBlock:(MyBlock)str;

@end

 

SecondView.m

#import "SecondView.h"



@implementation SecondView



-(id)initwithBlock:(MyBlock)str

{

    self = [super init];

    if(self)

    {   

        my = str;

    }

    return self;

}

-(IBAction)back:(id)sender

{

    NSString* s = txtView.text;

    if(my)

    {

        my(s);

    }

    [self.navigationController popViewControllerAnimated:YES];

}



- (void)didReceiveMemoryWarning

{

    [super didReceiveMemoryWarning];

}

-(void)dealloc{

    Block_release(my);

    [super dealloc];

    

}

#pragma mark - View lifecycle



- (void)viewDidLoad

{

    [super viewDidLoad];

}



- (void)viewDidUnload

{

    [super viewDidUnload];

}



- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation

{

    return (interfaceOrientation == UIInterfaceOrientationPortrait);

}



@end

 

界面：