react-native/React/Modules/RCTEventEmitter.m
Sophie Alpert 1490ab12ef Update license headers for MIT license
Summary:
Includes React Native and its dependencies Fresco, Metro, and Yoga. Excludes samples/examples/docs.

find: ^(?:( *)|( *(?:[\*~#]|::))( )? *)?Copyright (?:\(c\) )?(\d{4})\b.+Facebook[\s\S]+?BSD[\s\S]+?(?:this source tree|the same directory)\.$
replace: $1$2$3Copyright (c) $4-present, Facebook, Inc.\n$2\n$1$2$3This source code is licensed under the MIT license found in the\n$1$2$3LICENSE file in the root directory of this source tree.

Reviewed By: TheSavior, yungsters

Differential Revision: D7007050

fbshipit-source-id: 37dd6bf0ffec0923bfc99c260bb330683f35553e
2018-02-16 18:31:53 -08:00

99 lines
2.5 KiB
Objective-C

/**
* Copyright (c) 2015-present, Facebook, Inc.
*
* This source code is licensed under the MIT license found in the
* LICENSE file in the root directory of this source tree.
*/
#import "RCTEventEmitter.h"
#import "RCTAssert.h"
#import "RCTUtils.h"
#import "RCTLog.h"
@implementation RCTEventEmitter
{
NSInteger _listenerCount;
}
+ (NSString *)moduleName
{
return @"";
}
+ (void)initialize
{
if (self != [RCTEventEmitter class]) {
RCTAssert(RCTClassOverridesInstanceMethod(self, @selector(supportedEvents)),
@"You must override the `supportedEvents` method of %@", self);
}
}
- (NSArray<NSString *> *)supportedEvents
{
return nil;
}
- (void)sendEventWithName:(NSString *)eventName body:(id)body
{
RCTAssert(_bridge != nil, @"Error when sending event: %@ with body: %@. "
"Bridge is not set. This is probably because you've "
"explicitly synthesized the bridge in %@, even though it's inherited "
"from RCTEventEmitter.", eventName, body, [self class]);
if (RCT_DEBUG && ![[self supportedEvents] containsObject:eventName]) {
RCTLogError(@"`%@` is not a supported event type for %@. Supported events are: `%@`",
eventName, [self class], [[self supportedEvents] componentsJoinedByString:@"`, `"]);
}
if (_listenerCount > 0) {
[_bridge enqueueJSCall:@"RCTDeviceEventEmitter"
method:@"emit"
args:body ? @[eventName, body] : @[eventName]
completion:NULL];
} else {
RCTLogWarn(@"Sending `%@` with no listeners registered.", eventName);
}
}
- (void)startObserving
{
// Does nothing
}
- (void)stopObserving
{
// Does nothing
}
- (void)dealloc
{
if (_listenerCount > 0) {
[self stopObserving];
}
}
RCT_EXPORT_METHOD(addListener:(NSString *)eventName)
{
if (RCT_DEBUG && ![[self supportedEvents] containsObject:eventName]) {
RCTLogError(@"`%@` is not a supported event type for %@. Supported events are: `%@`",
eventName, [self class], [[self supportedEvents] componentsJoinedByString:@"`, `"]);
}
_listenerCount++;
if (_listenerCount == 1) {
[self startObserving];
}
}
RCT_EXPORT_METHOD(removeListeners:(double)count)
{
int currentCount = (int)count;
if (RCT_DEBUG && currentCount > _listenerCount) {
RCTLogError(@"Attempted to remove more %@ listeners than added", [self class]);
}
_listenerCount = MAX(_listenerCount - currentCount, 0);
if (_listenerCount == 0) {
[self stopObserving];
}
}
@end