RAC(self.loginViewModel, userName) = self.userNameTF.rac_textSignal;
RAC(self.loginViewModel, password) = self.passwordTF.rac_textSignal;
@weakify(self)
[[self.loginButton rac_signalForControlEvents: UIControlEventTouchUpInside] subscribeNext:^(id x) {
@strongify(self)
if (self.loginViewModel.userName.length == 0) {
self.loginViewModel.alertTip = @"用户名不能为空";
return ;
}
if (self.loginViewModel.password.length == 0) {
self.loginViewModel.alertTip = @"密码不能为空";
return;
}
[self.loginViewModel clickLogin];
}];
[[RACObserve(self, alertTip) filter:^BOOL(NSString * value) {
return value.length != 0 && value;
}] subscribeNext:^(NSString * tip) {
Alert(tip);
}];
原文：http://www.cnblogs.com/qzp2014/p/5139544.html