iOS简单实现版本更新检测

//
//  HYBVersionManager.h
//
//  Created by 黄仪标 on 15/1/27.
//

#import <Foundation/Foundation.h>

// 应用已经发布到APP Store后才会在Itunes上有应用的链接
// 所以版本检测必须是已经发布过才能做
// 在真正实现功能时，需要替换成真正的链接
// @requared
#define kAppStoreLink  @""
#define kItunsLink @""

/*!
 * 版本管理器
 */
@interface HYBVersionManager : NSObject

/*!
 * @brief 单例方法
 */
+ (HYBVersionManager *)sharedVersionManager;

/*
 * 调用此方法来执行版本检测
 * @param type
 */
- (void)checkVersion:(int)type;

@end

//
//  HYBVersionManager.m
//
//  Created by 黄仪标 on 15/1/27.
//

#import "HYBVersionManager.h"
#import "UIAlertView+Blocks.h"

#define kRequestTimeOut 60.0

@interface HYBVersionManager () {
  int         _type;
  UIAlertView *_alertView;
}

@end

@implementation HYBVersionManager

/*!
 * @brief 单例方法
 */
+ (HYBVersionManager *)sharedVersionManager {
  static HYBVersionManager *sharedObject = nil;
  static dispatch_once_t onceToken;
  
  dispatch_once(&onceToken, ^{
    if (!sharedObject) {
      sharedObject = [[self alloc] init];
    }
  });
  
  return sharedObject;
}

- (instancetype)init {
  if (self = [super init]) {
    _type = 0; // 自动检测
  }
  return self;
}

- (void)checkVersion:(int)type {
  _type = type;
  
  [self checkAppStoreVersion];
}

- (void)checkAppStoreVersion {
  if ([NSThread isMainThread]) {
    [self performSelectorInBackground:@selector(checkAppStoreVersion) withObject:nil];
    return;
  }
  
  @autoreleasepool  {
    //prevent concurrent checks
    static BOOL checking = NO;
    
    if (checking) return;
    checking = YES;
    
    NSError *error = nil;
    NSURLResponse *response = nil;
    NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:kItunsLink]
                                             cachePolicy:NSURLRequestReturnCacheDataElseLoad
                                         timeoutInterval:kRequestTimeOut];
    NSData *data = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error];
    NSInteger statusCode = ((NSHTTPURLResponse *)response).statusCode;
    if (data && statusCode == 200) {
      error = nil;
      id json = nil;
      if ([NSJSONSerialization class]) {
        NSDictionary *dict = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableContainers error:&error];
        json = [dict[@"results"] lastObject];
      } else {
        json = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
      }
      
      if (!error) {
        // 获取到appstore上最新的版本号
        NSString *latestVersion = [self valueForKey:@"version" inJSON:json];
        NSString *localVersion = [self appLocalVersion];
        [self check:latestVersion localVersion:localVersion];
      }
    }
    
    // finished
    checking = NO;
  }
}

- (void)check:(NSString *)latestVersion localVersion:(NSString *)localVersion {
  if ([latestVersion compare:localVersion] == NSOrderedDescending) { // 有新版本
    [self showPromptForUpdate];
  } else if ([latestVersion compare:localVersion options:NSNumericSearch] == NSOrderedSame) {// 已经是最新版本
    if (_type == 1) { // 手动
      [self showMessage];
    }
  }
}

- (void)showMessage {
  if (_alertView) {
    _alertView.hidden = YES;
    [_alertView removeFromSuperview];
    _alertView = nil;
  }
  
  UIAlertView *alert = [UIAlertView showWithTitle:@""
                                          message:@"当前版本已经是最新版本！"
                                         okButton:@"确定"
                                     cancelButton:nil];
  _alertView = alert;
}

- (void)showPromptForUpdate {
  [UIAlertView showWithTitle:nil
                     message:@"有新版本发布了，亲，快去更新吧！"
           cancelButtonTitle:@"暂不更新"
           otherButtonTitles:@[@"立即更新"] tapBlock:^(UIAlertView *alertView, NSInteger buttonIndex) {
                                 if (buttonIndex == 0) {
                                   
                                 } else {
                                   [[UIApplication sharedApplication] openURL:[NSURL URLWithString:kAppStoreLink]];
                                 }
                               }];
}

/*!
 * @brief 获取app本地的版本号
 */
- (NSString *)appLocalVersion {
  NSDictionary *info = [[NSBundle mainBundle] infoDictionary];
  NSString *version = [info objectForKey:@"CFBundleVersion"];
  
  return [version stringByTrimmingCharactersInSet:[NSCharacterSet letterCharacterSet]];
}

- (NSString *)valueForKey:(NSString *)key inJSON:(id)json {
  if ([json isKindOfClass:[NSString class]]) {
    //use legacy parser
    NSRange keyRange = [json rangeOfString:[NSString stringWithFormat:@"\"%@\"", key]];
    if (keyRange.location != NSNotFound) {
      NSInteger start = keyRange.location + keyRange.length;
      NSRange valueStart = [json rangeOfString:@":" options:(NSStringCompareOptions)0 range:NSMakeRange(start, [(NSString *)json length] - start)];
      if (valueStart.location != NSNotFound) {
        start = valueStart.location + 1;
        NSRange valueEnd = [json rangeOfString:@"," options:(NSStringCompareOptions)0 range:NSMakeRange(start, [(NSString *)json length] - start)];
        if (valueEnd.location != NSNotFound) {
          NSString *value = [json substringWithRange:NSMakeRange(start, valueEnd.location - start)];
          value = [value stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
          while ([value hasPrefix:@"\""] && ![value hasSuffix:@"\""]) {
            if (valueEnd.location == NSNotFound) {
              break;
            }
            NSInteger newStart = valueEnd.location + 1;
            valueEnd = [json rangeOfString:@"," options:(NSStringCompareOptions)0 range:NSMakeRange(newStart, [(NSString *)json length] - newStart)];
            value = [json substringWithRange:NSMakeRange(start, valueEnd.location - start)];
            value = [value stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
          }
          
          value = [value stringByTrimmingCharactersInSet:[NSCharacterSet characterSetWithCharactersInString:@"\""]];
          value = [value stringByReplacingOccurrencesOfString:@"\\\\" withString:@"\\"];
          value = [value stringByReplacingOccurrencesOfString:@"\\/" withString:@"/"];
          value = [value stringByReplacingOccurrencesOfString:@"\\\"" withString:@"\""];
          value = [value stringByReplacingOccurrencesOfString:@"\\n" withString:@"\n"];
          value = [value stringByReplacingOccurrencesOfString:@"\\r" withString:@"\r"];
          value = [value stringByReplacingOccurrencesOfString:@"\\t" withString:@"\t"];
          value = [value stringByReplacingOccurrencesOfString:@"\\f" withString:@"\f"];
          value = [value stringByReplacingOccurrencesOfString:@"\\b" withString:@"\f"];
          
          while (YES) {
            NSRange unicode = [value rangeOfString:@"\\u"];
            if (unicode.location == NSNotFound || unicode.location + unicode.length == 0) {
              break;
            }
            
            uint32_t c = 0;
            NSString *hex = [value substringWithRange:NSMakeRange(unicode.location + 2, 4)];
            if (hex != nil) {
              NSScanner *scanner = [NSScanner scannerWithString:hex];
              [scanner scanHexInt:&c];
            }
            
            if (c <= 0xffff) {
              value = [value stringByReplacingCharactersInRange:NSMakeRange(unicode.location, 6) withString:[NSString stringWithFormat:@"%C", (unichar)c]];
            } else {
              //convert character to surrogate pair
              uint16_t x = (uint16_t)c;
              uint16_t u = (c >> 16) & ((1 << 5) - 1);
              uint16_t w = (uint16_t)u - 1;
              unichar high = 0xd800 | (w << 6) | x >> 10;
              unichar low = (uint16_t)(0xdc00 | (x & ((1 << 10) - 1)));
              
              value = [value stringByReplacingCharactersInRange:NSMakeRange(unicode.location, 6) withString:[NSString stringWithFormat:@"%C%C", high, low]];
            }
          }
          return value;
        }
      }
    }
  } else {
    return json[key];
  }
  return nil;
}

@end

这里功能很简单，一种是自动检测，也就是在应用启动的时候调用，

另一种是手动检测，一般是放在设置中的检查版本更新时，手动检测。