this is CrespoXiao's gists

AlertClass

//
//  TCNetworkAlertView.h
//  KanKanIphone
//
//  Created by CrespoXiao on 13-11-26.
//
//
 
#import <UIKit/UIKit.h>

@interface TCNetworkAlertView : UIView {
  UIButton* _netErrorButton;
  UILabel * _textLabel;
}
@property (nonatomic,assign)BOOL _is_try_again;
@property (nonatomic,assign)BOOL is_showing;
@property (nonatomic, copy) void(^tryAgainBlock)();

+ (TCNetworkAlertView *)sharedInstance;
- (void)showAlertWithText:(NSString*)str;
- (void)hide;

@end



//
//  TCNetworkAlertView.m
//  KanKanIphone
//
//  Created by CrespoXiao on 13-11-26.
//
//

#import "TCNetworkAlertView.h"
#import "TCAppDelegate.h"

static TCNetworkAlertView* netAlert = nil;
//static int try_count = 0;

@implementation TCNetworkAlertView
@synthesize _is_try_again;
@synthesize is_showing;

+ (TCNetworkAlertView*) sharedInstance{
  if (!netAlert) {
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
      netAlert = [[TCNetworkAlertView alloc]initWithFrame:CGRectMake(0, 20+44, SCREEN_WIDTH, SCREEN_HEIGHT-20-44-49)];
    });
  }
  return netAlert;
}

- (id)initWithFrame:(CGRect)frame
{
  self = [super initWithFrame:frame];
  if (self) {
   
    _netErrorButton = [UIButton buttonWithType:UIButtonTypeCustom];
    _netErrorButton.frame = CGRectMake(0, 0, SCREEN_WIDTH, SCREEN_HEIGHT-20-44);
    _netErrorButton.backgroundColor = [UIColor clearColor];
    [_netErrorButton setImage:[UIImage imageNamed:@""] forState:UIControlStateHighlighted];
    [_netErrorButton addTarget:self action:@selector(tryAgain) forControlEvents:UIControlEventTouchUpInside];
    [self addSubview:_netErrorButton];
   
    UIImageView * image = [[UIImageView alloc]initWithFrame:
                           CGRectMake(70, (SCREEN_HEIGHT-20-44-49)*(2.0/5.0), 24, 24)];
    image.image = [UIImage imageNamed:@"Warning.png"];
    [self addSubview:image];
   
   
    _textLabel = [[UILabel alloc] initWithFrame:CGRectMake(100, (SCREEN_HEIGHT-20-44-49)*(2.0/5.0), 200, 28)];
    _textLabel.backgroundColor = [UIColor clearColor];
    _textLabel.font = [UIFont boldSystemFontOfSize:14.0];
    _textLabel.textColor = TitleColor;
    [self addSubview:_textLabel];
  }
  return self;
}


- (void)showAlertWithText:(NSString*)str {
  if ([TCNetworkAlertView sharedInstance]) {
    [[TCNetworkAlertView sharedInstance] removeFromSuperview];
  }
  [[TCAppDelegate sharedInstance].window.rootViewController.view addSubview:[TCNetworkAlertView sharedInstance]];
  [[TCNetworkAlertView sharedInstance] show:str];
  [TCNetworkAlertView sharedInstance].is_showing = YES;
}


- (void)show:(NSString*)str {
  _textLabel.text = str;
  self.hidden = NO;
}



//user block instead of kvo

//- (void)tryAgain {
//  //_is_try_again = YES;
//  self._is_try_again = YES;
//
////  ++try_count;
////  if (try_count < 2) {
////    _is_try_again = YES;
////  }else {
////    try_count = 0;
////    //_is_try_again = YES; //only try 1 time ?
////  }
//  [self hide];
//}


- (void)tryAgain {
  if (_tryAgainBlock) {
    _tryAgainBlock();
    _tryAgainBlock = nil;
  }
  [self hide];
}


- (void)hide {
  self.is_showing = NO;
  [self removeFromSuperview];
}

@end 










//how to use ? see below


    [[TCNetworkAlertView sharedInstance]showAlertWithText:NSLocalizedString(@"home.network.error", nil)];
    //__block SubLoginView* weakSelf = self; //for no arc
    //__weak typeof(self) weakSelf = self;  //for arc
    __block __typeof(self) weakSelf = self; //for all
    [[TCNetworkAlertView sharedInstance] setTryAgainBlock:^{
      [weakSelf onConfirmButtonClicked];
    }];
   
//    [[TCNetworkAlertView sharedInstance] addObserver:self
//                                          forKeyPath:@"_is_try_again"
//                                             options:NSKeyValueObservingOptionNew
//                                             context:NULL];



//- (void)observeValueForKeyPath:(NSString *)keyPath
//                      ofObject:(id)object
//                        change:(NSDictionary *)change
//                       context:(void *)context
//{
//  DLog(@"%s", __FUNCTION__);
// 
//  if ([keyPath isEqualToString:@"_is_try_again"])
//  {
//    if (self.view.window) {
//      [self onConfirmButtonClicked];
//    }
//   
//  }
//}