iOS开发之ReactiveCocoa框架（RAC）第二篇登录实例

我们平时在做登录注册的时候，需要校验用户名和密码的textField输入内容，比如字符长度，设置textField的deleagte。用来设置Button是否可以被点击。
代码如下：

.h文件

#import "LoginViewViewController.h"@interface LoginViewViewController ()<UITextFieldDelegate>@property(nonatomic,strong)UILabel * nameLabel;@property(nonatomic,strong)UITextField * nameTextField;@property(nonatomic,strong)UILabel * passwordLbale;@property(nonatomic,strong)UITextField * passwordTextField;@property(nonatomic,strong)UIButton * loginButton;@end@implementation LoginViewViewController- (void)viewDidLoad {    [super viewDidLoad];    // Do any additional setup after loading the view.    self.view.backgroundColor =[UIColor whiteColor];    [self createUI];    [self.nameTextField setDelegate:self];    [self.passwordTextField setDelegate:self];   self.loginButton.enabled = NO;-(BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{    NSString * str =[textField.text stringByReplacingCharactersInRange:range withString:string];    NSString * s1 =self.nameTextField.text;    NSString * s2 =self.passwordTextField.text;    if (textField ==self.nameTextField) {        s1 = str;    }else{        s2 = str;    }    if (s1.length>0 && s2.length>6) {        self.loginButton.enabled = YES;    }else{        self.loginButton.enabled = NO;    }    NSLog(@"%@,%@",s1,s2);   return YES;}-(void)createUI{    self.nameLabel =[[UILabel alloc]initWithFrame:CGRectMake(50, 200, 100, 40)];    self.nameLabel.text = @"用户名:";    self.nameLabel.textColor =[UIColor blueColor];    [self.view addSubview:self.nameLabel];    self.nameTextField =[[UITextField alloc]initWithFrame:CGRectMake(120, 200, 200, 40)];    self.nameTextField.backgroundColor  =[UIColor grayColor];    [self.view addSubview:self.nameTextField];    self.passwordLbale =[[UILabel alloc]initWithFrame:CGRectMake(50, 260,100,40)];    self.passwordLbale.text =@"密码：";    self.passwordLbale.textColor =[UIColor blueColor];    [self.view addSubview:self.passwordLbale];    self.passwordTextField =[[UITextField alloc]initWithFrame:CGRectMake(120, 260, 200, 40)];    self.passwordTextField.backgroundColor  =[UIColor grayColor];    [self.view addSubview:self.passwordTextField];    self.loginButton =[[UIButton alloc]initWithFrame:CGRectMake((self.view.frame.size.width-100)/2, 400, 100, 50)];    [self.loginButton setTitle:@"登录" forState:UIControlStateNormal];    [self.loginButton setTitleColor:[UIColor blueColor] forState:UIControlStateNormal];    [self.view addSubview:self.loginButton];}

除了设置delegate的方法以外，还能使用RAC的处理方式。利用RAC处理事件很方便，可以把要处理的事情和监听的事情的代码放在一起，这样非常方便我们管理，就不需要跳到对应的方法里。
实例如下：
.h文件

#import "LoginViewViewController.h"@import ReactiveCocoa;//引用RAC@interface LoginViewViewController ()@property(nonatomic,strong)UILabel * nameLabel;@property(nonatomic,strong)UITextField * nameTextField;@property(nonatomic,strong)UILabel * passwordLbale;@property(nonatomic,strong)UITextField * passwordTextField;@property(nonatomic,strong)UIButton * loginButton;@end@implementation LoginViewViewController- (void)viewDidLoad {    [super viewDidLoad];    // Do any additional setup after loading the view.    self.view.backgroundColor =[UIColor whiteColor];    [self createUI];    //RAC方式    /*     // 展示：关于textField组件，RAC团队设置了一个专门取字符串的信号量。它跟使用回调去实现的方式是一样的。     [self.nameTextField.rac_textSignal subscribeNext:^(id x) {     NSLog(@"%@",x);     }];     */    /*     //一个输入框的处理     RACSignal * enableSignal =[self.nameTextField.rac_textSignal map:^id(NSString * value) {     return @(value.length > 0);     }];     */     RACSignal * enableSignal = [[RACSignal combineLatest:@[self.nameTextField.rac_textSignal,self.passwordTextField.rac_textSignal]] map:^id(id value) {        NSLog(@"%@",value);        return @([value[0] length]>0 && [value[1] length] >6);    }];    self.loginButton.rac_command =[[RACCommand alloc]initWithEnabled:enableSignal signalBlock:^RACSignal *(id input) {        return [RACSignal empty];    }];}