1

我正在尝试围绕 Reactive Cocoa，一切正常，除了RAC(self.windButton.enabled)部分（在底部），reduce 块永远不会被调用。如果有人能指出我的错误，我会很高兴。代码是不言自明的，基本上app是这样的：

应用截图

这是实现

#import "ViewController.h"

@interface ViewController ()

@property (strong, nonatomic) NSNumber *winding;
@property (strong, nonatomic) NSNumber *minWinding;
@property (strong, nonatomic) NSNumber *maxWinding;

@property (weak, nonatomic) IBOutlet UIButton *windButton;
@property (weak, nonatomic) IBOutlet UIButton *unwindButton;
@property (weak, nonatomic) IBOutlet UILabel *windingLabel;

@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];

    self.winding = @0;
    self.minWinding = @0;
    self.maxWinding = @15;

    RACSignal *windingSignal = RACAble(self.winding);
    RACSignal *maxWindingSignal = RACAble(self.maxWinding);
    RACSignal *minWindingSignal = RACAble(self.minWinding);

    RAC(self.windingLabel.text) = [windingSignal map:^id(NSNumber *winding) {
        return winding.stringValue;
    }];

    [[self.windButton rac_signalForControlEvents:UIControlEventTouchUpInside]
     subscribeNext:^(id sender) {
        self.winding = @(self.winding.integerValue + 1);
    }];

    [[self.unwindButton rac_signalForControlEvents:UIControlEventTouchUpInside]
     subscribeNext:^(id sender) {
        self.winding = @(self.winding.integerValue - 1);
    }];

    RAC(self.windButton.enabled) = [RACSignal
                              combineLatest:@[windingSignal, maxWindingSignal]
                              reduce:^(NSNumber *winding, NSNumber *maxWinding) {
                                  return @(winding.intValue < maxWinding.intValue);
                              }];


    RAC(self.unwindButton.enabled) = [RACSignal
                               combineLatest:@[windingSignal, minWindingSignal]
                               reduce:^(NSNumber *winding, NSNumber *minWinding) {
                                   return @(winding.intValue > minWinding.intValue);
                               }];
}

我的问题是按钮永远不会被禁用。

4

2 回答 2

1

我不得不使用RACAbleWithStart初始值来预填充信号，因为combineLatest方法会等到每个提供的信号都有一些值。

RACSignal *windingSignal = RACAbleWithStart(self.winding);
RACSignal *maxWindingSignal = RACAbleWithStart(self.maxWinding);
RACSignal *minWindingSignal = RACAbleWithStart(self.minWinding);
于 2013-09-01T22:25:36.510 回答
0

RAC() 宏至少需要两个参数。

看看这个问题

于 2014-02-13T16:15:59.990 回答