UIAlertView 只弹一次实现

思路：把所有创建的alertView都存储在数组里。。。遍历保留最后一个😂

Talk is cheap. Show me the code

环信EMAlertView EMAlertView类文件地址

MXAlertViewManager 单例的实现方式如下：

#import "MXAlertViewManager.h"
#import "EMAlertView.h"

@interface MXAlertViewManager ()

@property (nonatomic, strong) NSMutableArray *alertArray;

@end

@implementation MXAlertViewManager

+ (instancetype)sharedInstance
{
    static MXAlertViewManager *_sharedManager = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        _sharedManager = [[self alloc] init];
    });
    return _sharedManager;
}

- (instancetype)init
{
    if (self == [super init]) {
        _alertArray = [NSMutableArray array];
    }
    return self;
}

- (void)alertCount:(EMAlertView *)alertView
{
    [self.alertArray addObject:alertView];

    if (self.alertArray.count > 1) {
        for (NSInteger i=0; i<self.alertArray.count-1; i++) {
            EMAlertView *alertView = self.alertArray[i];
            [alertView dismissWithClickedButtonIndex:-1 animated:YES];
        }
    }
}

@end```

[iOS dismiss UIAlertView beforing showing another](http://stackoverflow.com/questions/5399219/ios-dismiss-uialertview-beforing-showing-another)  从`stackoverflow`搜索的类似跟我的问题描述
或者你用`runtime`拦截`show`方法

^_^ 如果有其他更好的想法，欢迎提出，共同进步。。。