用rac_signalForSelector 代替textField:shouldChangeCharactersInRange:replacementString :时无法输入

[jackson0122]

_textField = [UITextField new];
_textField.frame = CGRectMake(50, 50, 200, 30);
_textField.backgroundColor = [UIColor cyanColor];
_textField.delegate = self;
[self.view addSubview:_textField];

[[self rac_signalForSelector:@selector(textField:shouldChangeCharactersInRange:replacementString:) fromProtocol:@protocol(UITextFieldDelegate)] subscribeNext:^(RACTuple *x) {
    NSLog(@"_____%@",x);
}];

output:
2019-03-23 17:49:59.611420+0800 LLKit[18454:188204] _____<RACTuple: 0x600000314290> (
"<UITextField: 0x7f8601032400; frame = (50 50; 200 30); text = ''; opaque = NO; gestureRecognizers = <NSArray: 0x600000f4e3a0>; layer = <CALayer: 0x600000144760>>",
"NSRange: {0, 0}",
S
)
2019-03-23 17:49:59.777225+0800 LLKit[18454:188204] _____<RACTuple: 0x60000030add0> (
"<UITextField: 0x7f8601032400; frame = (50 50; 200 30); text = ''; opaque = NO; gestureRecognizers = <NSArray: 0x600000f4e3a0>; layer = <CALayer: 0x600000144760>>",
"NSRange: {0, 0}",
S
)