ReactiveCocoa系列-隐藏显示placehold

来源：互联网发布：h3c路由器端口映射 sql 编辑：程序博客网时间：2024/06/06 02:08

        //创建textField获得焦点信号,当信号发生时返回@YES        RACSignal *didBeginEditingSignal = [[self rac_signalForSelector:@selector(textFieldDidBeginEditing:) fromProtocol:@protocol(UITextFieldDelegate)] mapReplace:@YES];                //创建textField失去焦点信号,当信号发生时返回@NO        RACSignal *didEndEditingSignal = [[self rac_signalForSelector:@selector(textFieldDidEndEditing:) fromProtocol:@protocol(UITextFieldDelegate)] mapReplace:@NO];                //合并两种信号到一个信号        RACSignal *userTextSignal = [RACSignal merge:@[didBeginEditingSignal, didEndEditingSignal]];                //doNext是信号发生时注入的边界触发.hiden为label的属性        RAC(placehold, hidden) = [userTextSignal doNext:^(id x) {            NSLog(@"toggle placehold. %@",x);        }];

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