基于FMDatabase的一层很薄的封装，主要目的是消除反复open close数据库的冗余代码，并以单例的形式暴露

#import "YLSDatabaseHelper.h"
#import "YLSGlobalUtils.h"

@implementation YLSDatabaseHelper

{
    FMDatabase* db;
}

-(id) init
{
    self = [super init];
    if(self){
        NSString *dbFilePath = [YLSGlobalUtils getDatabaseFilePath];
        db = [[FMDatabase alloc] initWithPath:dbFilePath];
    }
    return self;
}

+(YLSDatabaseHelper*) sharedInstance
{
    static dispatch_once_t pred = 0;
    __strong static id _sharedObject = nil;
    dispatch_once(&pred,^{
        _sharedObject = [[self alloc] init];
    });
    return _sharedObject;
}

-(void) doOperation:(void(^)(FMDatabase*))block
{
    [db open];
    block(db);
    [db close];
}

@end