iOS应用商店升级检查：简单实用代码示例

- (void)checkVersion {
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        dispatch_async(dispatch_get_main_queue(), ^ {
            [self startMaskViewWithDescStr:NSLocalizedString(@"检测中", @"") tag:0 withUserData:nil];
        });
        NSURL *URL =  [NSURL URLWithString:@"http://itunes.apple.com/lookup?id=948496255"];
        NSMutableURLRequest *request = [[NSMutableURLRequest alloc] init];
        [request setURL:URL];
        [request setHTTPMethod:@"POST"];
        NSHTTPURLResponse *urlResponse = nil;
        NSError *error = nil;
        NSData *recervedData = [NSURLConnection sendSynchronousRequest:request returningResponse:&urlResponse error:&error];
        if (error != nil) {//出错了
            dispatch_async(dispatch_get_main_queue(), ^{
                [maskView fakeFromSuperviewAtOnce];
                maskView = nil;
                TipsView *tipsView = [[TipsView alloc] init];
                [tipsView setTipsStr:[NSString stringWithFormat:@"%@",[error localizedDescription]]];
                [tipsView showAnimated:YES];
            });
        } else {
            NSString *results = [[NSString alloc] initWithBytes:[recervedData bytes] length:[recervedData length] encoding:NSUTF8StringEncoding];
            NSDictionary *dic = [results JSONValue];
            NSArray *infoArray = [dic objectForKey:@"results"];
            if ([infoArray count]) {
                NSDictionary *releaseInfo = [infoArray objectAtIndex:0];
                NSString *lastVersion = [releaseInfo objectForKey:@"version"];
                if (![lastVersion isEqualToString:CURRENT_VERSION]) {
                    dispatch_async(dispatch_get_main_queue(), ^{
                        [maskView fakeFromSuperviewAtOnce];