该崩溃报错是由于写法不规范导致的
一、官方文档和不合理想法
1.官方文档
// CalendarManager.h
#import <React/RCTEventEmitter.h>
@interface CalendarManager : RCTEventEmitter <RCTBridgeModule>
@end
// CalendarManager.m
#import "CalendarManager.h"
@implementation CalendarManager
RCT_EXPORT_MODULE()
- (NSArray<NSString *> *)supportedEvents {
return @[@"EventReminder"];
}
- (void)calendarEventReminderReceived:(NSNotification *)notification {
NSString *eventName = notification.userInfo[@"name"];
[self sendEventWithName:@"EventReminder" body:@{@"name": eventName}];
}
@end
2.不合理想法
由于该文档只是点明了calendarEventReminderReceived方法传的参数是NSNotification类型，我并没有在意这个类型，于是我的做法是在.h中暴露该方法- (void)calendarEventReminderReceived:(NSNotification *)notification;，等我想给JS发消息的时候，直接调用这个方法即可。
二、分析错误
1.初步断定是OC代码的问题
崩溃的意思是没有建立桥接，由于本人从来没有接触过RN，也没写过JS代码，一开始不知道到底是OC的代码有问题，还是JS的代码有问题，通过阅读RCTEventEmitter类的代码发现，可以在CalendarManager.m中重写- (void)startObserving方法和- (void)stopObserving方法来判断JS代码是否写正确。如果JS代码执行addListener添加监听的时候，OC执行了startObserving方法，则证明JS代码没问题。
2.打印桥接属性，判断崩溃原因
阅读RCTEventEmitter类的代码可以发现，该类有一个bridge属性，于是我在startObserving和calendarEventReminderReceived方法里分别打印self.bridge，发现startObserving中有bridge，而calendarEventReminderReceived中为空，什么都没做bridge不可能凭空消失,然后我又分别打印了self，果然，startObserving和calendarEventReminderReceived中打印的self是不一样的。
由此可以知道：当JS代码执行addListener添加监听的时候，就会通过alloc init创建一个CalendarManager对象并建立桥接，我们自己创建的对象是没有桥接的，所以就崩溃了。
三、解决错误
既然找到错误原因了，那就好说了，首先想到的解决办法应该是单例，在CalendarManager.m中添加如下代码即可避免崩溃。
static id _instace;
+ (instancetype)allocWithZone:(struct _NSZone *)zone {
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
_instace = [super allocWithZone:zone];
});
return _instace;
}
四、优化（合理思路和规范写法）
当我写完单例的时候，我突然想到了官方文档中calendarEventReminderReceived方法传的参数类型是NSNotification。我用OC给JS发送消息的时候，也是用的NSNotificationCenter，当收到通知的时候，我创建一个CalendarManager对象来调calendarEventReminderReceived方法。
这个时候，我突然想扇自己一巴掌：为什么要做这脱裤子放屁的事。直接在CalendarManager的init方法里面添加通知的监听不就完了吗。。。而且这样不用在别的地方创建CalendarManager对象了，也不用在CalendarManager.m中重写allocWithZone方法来创建单例了😅
- (instancetype)init {
if (self = [super init]) {
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(calendarEventReminderReceived:) name:@"customNotificationName" object:nil];
}
return self;
}
附：
一、二、崩溃报错代码
// CalendarManager.h
#import <React/RCTEventEmitter.h>
@interface CalendarManager : RCTEventEmitter <RCTBridgeModule>
- (void)calendarEventReminderReceived:(NSNotification *)notification;
@end
// CalendarManager.m
#import "CalendarManager.h"
@implementation CalendarManager
RCT_EXPORT_MODULE()
- (NSArray<NSString *> *)supportedEvents {
return @[@"EventReminder"];
}
- (void)calendarEventReminderReceived:(NSNotification *)notification {
NSString *eventName = notification.userInfo[@"name"];
[self sendEventWithName:@"EventReminder" body:@{@"name": eventName}];
}
@end
// AppDelegate.m
#import "AppDelegate.h"
#import "CalendarManager.h"
@interface AppDelegate ()
@end
@implementation AppDelegate
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(calendarReceived:) name:@"customNotificationName" object:nil];
return YES;
}
- (void)calendarReceived:(NSNotification *)notification {
[[CalendarManager new] calendarEventReminderReceived:notification];
}
三、解决崩溃代码
// CalendarManager.h
#import <React/RCTEventEmitter.h>
@interface CalendarManager : RCTEventEmitter <RCTBridgeModule>
- (void)calendarEventReminderReceived:(NSNotification *)notification;
@end
// CalendarManager.m
#import "CalendarManager.h"
@implementation CalendarManager
RCT_EXPORT_MODULE()
static id _instace;
+ (instancetype)allocWithZone:(struct _NSZone *)zone {
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
_instace = [super allocWithZone:zone];
});
return _instace;
}
- (NSArray<NSString *> *)supportedEvents {
return @[@"EventReminder"];
}
- (void)calendarEventReminderReceived:(NSNotification *)notification {
NSString *eventName = notification.userInfo[@"name"];
[self sendEventWithName:@"EventReminder" body:@{@"name": eventName}];
}
@end
// AppDelegate.m
#import "AppDelegate.h"
#import "CalendarManager.h"
@interface AppDelegate ()
@end
@implementation AppDelegate
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(calendarReceived:) name:@"customNotificationName" object:nil];
return YES;
}
- (void)calendarReceived:(NSNotification *)notification {
[[CalendarManager new] calendarEventReminderReceived:notification];
}
四、优化之后代码
// CalendarManager.h
#import <React/RCTEventEmitter.h>
@interface CalendarManager : RCTEventEmitter <RCTBridgeModule>
@end
// CalendarManager.m
#import "CalendarManager.h"
@implementation CalendarManager
RCT_EXPORT_MODULE()
- (instancetype)init {
if (self = [super init]) {
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(calendarEventReminderReceived:) name:@"customNotificationName" object:nil];
}
return self;
}
- (void)dealloc {
[[NSNotificationCenter defaultCenter] removeObserver:self name:@"customNotificationName" object:nil];
}
- (NSArray<NSString *> *)supportedEvents {
return @[@"EventReminder"];
}
- (void)calendarEventReminderReceived:(NSNotification *)notification {
NSString *eventName = notification.userInfo[@"name"];
[self sendEventWithName:@"EventReminder" body:@{@"name": eventName}];
}
@end
JS代码
import {NativeModules, NativeEventEmitter} from 'react-native';
const CalendarManager = new NativeEventEmitter(NativeModules.CalendarManager);
CalendarManager.addListener('EventReminder',(str) => {
alert(str);
});
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