使用 ReactiveCocoa 将信号值收集到数组中

Question

我使用 ReactiveCocoa 来记录数组中的点击：

@interface ViewController : UIViewController
@property (strong, nonatomic) NSArray *first10Taps;
@property (strong, nonatomic) UITapGestureRecognizer *tapGesture;
@end

@implementation ViewController
- (void) viewDidLoad
{
  [super viewDidLoad];

  RACSignal *tapSignal = [[self.tapGesture rac_gestureSignal] map:^id(UITapGestureRecognizer *sender) {
    return [NSValue valueWithCGPoint:[sender locationInView:sender.view]];
  }];

  // This signal will send the first 10 tapping positions and then send completed signal.
  RACSignal *first10TapSignal = [tapSignal take:10];

  // Need to turn this signal to a sequence with the first 10 taps.
  RAC(self, first10Taps) = [first10TapSignal ...];
}
@end

如何将此信号转为阵列信号？

每次发送新值时我都需要更新数组。

Answer 1

RACSignal 上有一个方法叫做 collect。它的文档说：

Collects all receiver's nexts into a NSArray. Nil values will be converted to NSNull. This corresponds to the ToArray method in Rx. Returns a signal which sends a single NSArray when the receiver completes successfully.

所以你可以简单地使用：

RAC(self, first10Taps) = [first10TapSignal collect];

Answer 2

感谢 Michał Ciuba 的回答。使用-collect只会在上行信号完成时才发送采集值。

我找到了使用 -scanWithStart:reduce: 产生信号的方法，该信号会在每次发送 next 值时发送集合。

RAC(self, first10Taps) = [firstTapSetSignal scanWithStart:[NSMutableArray array]  reduce:^id(NSMutableArray *collectedValues, id next) {
  [collectedValues addObject:(next ?: NSNull.null)];
  return collectedValues;
}];

使用 ReactiveCocoa 将信号值收集到数组中

Collect signal values to an array using ReactiveCocoa

objective-c

reactive-cocoa