RootViewController.m

- (void)viewDidLoad
{
    [super viewDidLoad];
    
    self.view.backgroundColor = [UIColor greenColor];
    
    //创建显示文字的label
    UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(50, 100, 200, 40)];
    label.tag = 102;
    label.backgroundColor = [UIColor grayColor];
    [self.view addSubview:label];
    [label release];
    
    //添加按钮
    UIButton *button = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    button.frame = CGRectMake(20, 20, 90, 60);
    [button setTitle:@"打开模态" forState:UIControlStateNormal];
    [button addTarget:self action:@selector(buttonAction) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:button];
    
    
}

- (void)viewWillAppear:(BOOL)animated {

    
     UILabel *label = (UILabel *)[self.view viewWithTag:102];
    
    //创建单例对象
    BackData *backData = http://www.mamicode.com/[BackData shareData];>ModalViewController.m
#import "BackData.h"

@interface ModalViewController ()

@end

@implementation ModalViewController

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    
    self.view.backgroundColor = [UIColor redColor];
    
    //添加按钮
    UIButton *button = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    button.frame = CGRectMake(20, 20, 90, 60);
    [button setTitle:@"关闭模态" forState:UIControlStateNormal];
    [button addTarget:self action:@selector(buttonAction) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:button];
    
    //创建输入框
    UITextField *textField = [[UITextField alloc] initWithFrame:CGRectMake(50, 100, 200, 40)];
    textField.tag = 101;
    textField.borderStyle = UITextBorderStyleRoundedRect;
    [self.view addSubview:textField];
    [textField release];
    
    
}

- (void)buttonAction {
    
    UITextField *field = (UITextField *)[self.view viewWithTag:101];
    
    //创建单例对象
    BackData *data = http://www.mamicode.com/[BackData shareData];>
BackData.h
@interface BackData : NSObject

@property (nonatomic, copy) NSString *text;

+ (BackData *)shareData;

BackData.m
static BackData *data = http://www.mamicode.com/nil;>



单例---视图间数据的传递：标签显示输入的内容【多个视图中】