ios 监听数组个数的变化_iOS观察者模式，监听数组变化

@interface ArrayModel : NSObject

@property (strong,nonatomic)NSMutableArray *voiceStrArray;

@end

@implementation ArrayModel

-(NSMutableArray *)voiceStrArray{

if(!_voiceStrArray){

_voiceStrArray = [NSMutableArray array];

}

return _voiceStrArray;

}

@end

@interface VoicePlayHelper (){

}

@property (nonatomic, strong)ArrayModel *arrayModel;

@end

@implementation VoicePlayHelper

+ (VoicePlayHelper *)sharedInstance{

static dispatch_once_t onceToken;

static VoicePlayHelper *_notiCenter = nil;

dispatch_once(&onceToken,^{

_notiCenter = [[super allocWithZone:NULL] init];

});

return _notiCenter;

}

+ (id)allocWithZone:(struct _NSZone *)zone{

return [self sharedInstance];

}

#pragma - implement NSCopying

- (id)copyWithZone:(NSZone *)zone

{

return self;

}

- (id)init

{

if ((self=[super init]))

{

arrCount = 1;

[self addObserver];

}

return self;

}

- (void)dealloc {

[_arrayModel removeObserver:self forKeyPath:@"voiceStrArray" context:NULL];

}

- (void)addObserver

{

_arrayModel = [ArrayModel new];

[_arrayModel addObserver:self forKeyPath:@"voiceStrArray" options:NSKeyValueObservingOptionNew|NSKeyValueObservingOptionOld context:NULL];

}

-(void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context{

NSLog(@"%@",change);

//一旦key值对应的value改变，

if ([keyPath isEqualToString:@"voiceStrArray"]) {

NSLog(@"数组发生变化:变成%lu个",(unsigned long)_arrayModel.voiceStrArray.count);

if (_arrayModel.voiceStrArray.count > 0 ) {

}

}

}