[英]UITextFieldDelegate textFieldShouldReturn with ReactiveCocoa
我正在尝试使用ReactiveCocoa实现UITextFieldDelegate textFieldShouldReturn处理。 不幸的是,当我订阅信号时,subscribeNext块会运行。
使用委派的实现将是:
- (void)viewDidLoad
{
...
self.myTextField.delegate = self;
}
...
- (BOOL)textFieldShouldReturn:(UITextField *)textField
{
if (textField == self.myTextField) {
NSLog(@"Let's go!");
}
return YES;
}
在ReactiveCocoa中,我以类似UITextView + RACSignalSupport的方式为UITextField添加了类别。
@implementation UITextField (RACKeyboardSupport)
static void RACUseDelegateProxy(UITextField *self)
{
if (self.delegate == self.rac_delegateProxy) return;
self.rac_delegateProxy.rac_proxiedDelegate = self.delegate;
self.delegate = (id)self.rac_delegateProxy;
}
- (RACDelegateProxy *)rac_delegateProxy
{
RACDelegateProxy *proxy = objc_getAssociatedObject(self, _cmd);
if (proxy == nil) {
proxy = [[RACDelegateProxy alloc] initWithProtocol:@protocol(UITextFieldDelegate)];
objc_setAssociatedObject(self, _cmd, proxy, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}
return proxy;
}
- (RACSignal *)rac_keyboardReturnSignal
{
@weakify(self);
RACSignal *signal = [[[[RACSignal
defer:^{
@strongify(self);
return [RACSignal return:RACTuplePack(self)];
}]
concat:[self.rac_delegateProxy signalForSelector:@selector(textFieldShouldReturn:)]]
takeUntil:self.rac_willDeallocSignal]
setNameWithFormat:@"%@ -rac_keyboardReturnSignal", [self rac_description]];
RACUseDelegateProxy(self);
return signal;
}
@end
即使从未按下回车键,在这里也会执行subscribeNext块:
- (void)viewDidLoad
{
...
[self.myTextField.rac_keyboardReturnSignal subscribeNext:^(id x) {
Log(@"Let's go with RAC!");
}];
}
我必须使用skip:1来避免该问题:
- (void)viewDidLoad
{
...
[[self.myTextField.rac_keyboardReturnSignal skip:1] subscribeNext:^(id x) {
Log(@"Let's go with RAC!");
}];
}
知道为什么会这样吗?
解:
- (RACSignal *)rac_keyboardReturnSignal
{
RACSignal *signal = [[[self.rac_delegateProxy
signalForSelector:@selector(textFieldShouldReturn:)]
takeUntil:self.rac_willDeallocSignal]
setNameWithFormat:@"%@ -rac_keyboardReturnSignal", [self rac_description]];
RACUseDelegateProxy(self);
return signal;
}
您正在返回立即在你返回一个值的信号defer
块,然后concat
当-ing新值到流textFieldShouldReturn
被调用。
UITextView+RACSignalSupport.m
的代码正在调用reduceEach
,以返回从UITextView
实例提取的字符串值。 defer
仅用于具有在订阅时生成的初始值。
基本上,我不认为你需要的defer
都为您的使用情况。
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