基于多年 iOS 开发经验，本文总结多条实用技能，希望对大家有所助益。

1、禁止手机睡眠

[UIApplication sharedApplication].idleTimerDisabled = YES;

2、隐藏某行cell

• (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
  {
  // 如果是你需要隐藏的那一行，返回高度为0
  if(indexPath.row == YouWantToHideRow)
  return 0;
  return 44;
  }

// 然后再你需要隐藏cell的时候调用
[self.tableView beginUpdates];
[self.tableView endUpdates];

3、禁用button高亮

button.adjustsImageWhenHighlighted = NO;
或者在创建的时候
UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];

4、tableview遇到这种报错failed to obtain a cell from its dataSource

是因为你的cell被调用的早了。先循环使用了cell，后又创建cell。顺序错了。可能原因：
xib的cell没有注册

内存中已经有这个cell的缓存了(也就是说通过你的cellId找到的cell并不是你想要的类型)，这时候需要改下cell的标识

5、cocoa pods报这个错误：unable to access 'https://github.com/facebook/pop.git/': Operation timed out after 0 milliseconds with 0 out of 0 bytes received

解决办法：原因可能是网络问题，网络请求超时了，只需要重试就行了

6、cocoa pods 出现ERROR: While executing gem ... (Errno::EPERM)

解决办法：
https://segmentfault.com/q/1010000002926243

7、动画切换window的根控制器

// options是动画选项
[UIView transitionWithView:[UIApplication sharedApplication].keyWindow duration:0.5f options:UIViewAnimationOptionTransitionCrossDissolve animations:^{
BOOL oldState = [UIView areAnimationsEnabled];
[UIView setAnimationsEnabled:NO];
[UIApplication sharedApplication].keyWindow.rootViewController = [RootViewController new];
[UIView setAnimationsEnabled:oldState];
} completion:^(BOOL finished) {

}];

8、去除数组中重复的对象

NSArray *newArr = [oldArr valueForKeyPath:@“@distinctUnionOfObjects.self"];

9、编译的时候遇到 no such file or directory: ／users／apple／XXX

是因为编译的时候，在此路径下找不到这个文件，解决这个问题，首先是是要检查缺少的文件是不是在工程中，如果不在工程中，需要从本地拖进去，如果发现已经存在工程中了，或者拖进去还是报错，这时候需要去build phases中搜索这个文件，这时候很可能会搜出现两个相同的文件，这时候，有一个路径是正确的，删除另外一个即可。如果删除了还是不行，需要把两个都删掉，然后重新往工程里拖进这个文件即可

10、iOS8系统中，tableView最好实现下-tableView: heightForRowAtIndexPath:这个代理方法，要不然在iOS8中可能就会出现显示不全或者无法响应事件的问题

11、iOS8中实现侧滑功能的时候这个方法必须实现，要不然在iOS8中无法侧滑

// 必须写的方法，和editActionsForRowAtIndexPath配对使用，里面什么不写也行

• (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {
  }

12、三个通知

NSSystemTimeZoneDidChangeNotification监听修改时间界面的两个按钮状态变化
UIApplicationSignificantTimeChangeNotification 监听用户改变时间 （只要点击自动设置按钮就会调用） NSSystemClockDidChangeNotification 监听用户修改时间（时间不同才会调用）

13、SDWebImage本地缓存有时候会害人。如果之前缓存过一张图片，即使下次服务器换了这张图片，但是图片url没换，用sdwebimage下载下来的还是以前那张,所以遇到这种问题，不要先去怼服务器，清空下缓存再试就好了。

14、上线前注意：

1）、删掉代码中所有的测试代码
2）、如果后台有审核模式，提醒后台开启此模式
3）、主流程再跑一跑
4）、全局搜索waring，检查所有标记waring的地方

15、跳进app权限设置

// 跳进app设置
if (UIApplicationOpenSettingsURLString != NULL) {
NSURL *url = [NSURL URLWithString:UIApplicationOpenSettingsURLString];
[[UIApplication sharedApplication] openURL:url];
}
}

16、给一个view截图

UIGraphicsBeginImageContextWithOptions(view.bounds.size, YES, 0.0);
[view.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *img = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

17、开发中如果要动态修改tableView的tableHeaderView或者tableFooterView的高度，需要给tableView重新设置，而不是直接更改高度。正确的做法是重新设置一下tableView.tableFooterView = 更改过高度的view。为什么？其实在iOS8以上直接改高度是没有问题的，在iOS8中出现了contentSize不准确的问题，这是解决办法。

18、注意对象为nil的时候，调用此对象分类的方法不会执行。

19、collectionView的内容小于其宽高的时候是不能滚动的，设置可以滚动：

collectionView.alwaysBounceHorizontal = YES;
collectionView.alwaysBounceVertical = YES;

20、设置navigationBar上的title颜色和大小

[self.navigationController.navigationBar setTitleTextAttributes:@{NSForegroundColorAttributeName : [UIColor youColor], NSFontAttributeName : [UIFont systemFontOfSize:15]}]

21、颜色转图片

• (UIImage *)cl_imageWithColor:(UIColor *)color {
  CGRect rect = CGRectMake(0.0f, 0.0f, 1.0f, 1.0f);
  UIGraphicsBeginImageContext(rect.size);
  CGContextRef context = UIGraphicsGetCurrentContext();

  CGContextSetFillColorWithColor(context, [color CGColor]);
  CGContextFillRect(context, rect);

  UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
  UIGraphicsEndImageContext();

  return image;
  }

22、view设置圆角

define ViewBorderRadius(View, Radius, Width, Color)\

[View.layer setCornerRadius:(Radius)];
[View.layer setMasksToBounds:YES];
[View.layer setBorderWidth:(Width)];
[View.layer setBorderColor:[Color CGColor]] // view圆角

23、强／弱引用

define WeakSelf(type) __weak typeof(type) weak##type = type; // weak

define StrongSelf(type) __strong typeof(type) type = weak##type; // strong

24、由角度转换弧度

define DegreesToRadian(x) (M_PI * (x) / 180.0)

25、由弧度转换角度

define RadianToDegrees(radian) (radian*180.0)/(M_PI)

26、获取图片资源

define GetImage(imageName) [UIImage imageNamed:[NSString stringWithFormat:@"%@",imageName]]

27、获取temp

define PathTemp NSTemporaryDirectory()

28、获取沙盒 Document

define PathDocument [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject]

29、获取沙盒 Cache

define PathCache [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) firstObject]

30、GCD代码只执行一次

define kDISPATCH_ONCE_BLOCK(onceBlock) static dispatch_once_t onceToken; dispatch_once(&onceToken, onceBlock);

31、自定义NSLog

ifdef DEBUG

define NSLog(fmt, ...) NSLog((@"%s [Line %d] " fmt), PRETTY_FUNCTION, LINE, ##VA_ARGS)

else

define NSLog(...)

endif

32、Font

define FontL(s) [UIFont systemFontOfSize:s weight:UIFontWeightLight]

define FontR(s) [UIFont systemFontOfSize:s weight:UIFontWeightRegular]

define FontB(s) [UIFont systemFontOfSize:s weight:UIFontWeightBold]

define FontT(s) [UIFont systemFontOfSize:s weight:UIFontWeightThin]

define Font(s) FontL(s)

33、FORMAT

define FORMAT(f, ...) [NSString stringWithFormat:f, ## VA_ARGS]

34、在主线程上运行

define kDISPATCH_MAIN_THREAD(mainQueueBlock) dispatch_async(dispatch_get_main_queue(), mainQueueBlock);

35、开启异步线程

define kDISPATCH_GLOBAL_QUEUE_DEFAULT(globalQueueBlock) dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), globalQueueBlocl);

36、通知

define NOTIF_ADD(n, f) [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(f) name:n object:nil]

define NOTIF_POST(n, o) [[NSNotificationCenter defaultCenter] postNotificationName:n object:o]

define NOTIF_REMV() [[NSNotificationCenter defaultCenter] removeObserver:self]

37、随机颜色

• (UIColor *)RandomColor {
  NSInteger aRedValue = arc4random() % 255;
  NSInteger aGreenValue = arc4random() % 255;
  NSInteger aBlueValue = arc4random() % 255;
  UIColor *randColor = [UIColor colorWithRed:aRedValue / 255.0f green:aGreenValue / 255.0f blue:aBlueValue / 255.0f alpha:1.0f];
  return randColor;
  }

38、获取window

+(UIWindow)getWindow {
UIWindow win = nil; //[UIApplication sharedApplication].keyWindow;
for (id item in [UIApplication sharedApplication].windows) {
if ([item class] == [UIWindow class]) {
if (!((UIWindow*)item).hidden) {
win = item;
break;
}
}
}
return win;
}

39、修改textField的placeholder的字体颜色、大小

[textField setValue:[UIColor redColor] forKeyPath:@"_placeholderLabel.textColor"];
[textField setValue:[UIFont boldSystemFontOfSize:16] forKeyPath:@"_placeholderLabel.font"];

40、统一收起键盘

[[[UIApplication sharedApplication] keyWindow] endEditing:YES];

41、控制屏幕旋转，在控制器中写

/** 是否支持自动转屏 */

• (BOOL)shouldAutorotate {
  return YES;
  }

/** 支持哪些屏幕方向 */

• (UIInterfaceOrientationMask)supportedInterfaceOrientations {
  return UIInterfaceOrientationMaskLandscapeLeft | UIInterfaceOrientationMaskLandscapeRight;
  }

/** 默认的屏幕方向（当前ViewController必须是通过模态出来的UIViewController（模态带导航的无效）方式展现出来的，才会调用这个方法） */

• (UIInterfaceOrientation)preferredInterfaceOrientationForPresentation {
  return UIInterfaceOrientationLandscapeLeft | UIInterfaceOrientationLandscapeRight;
  }

42、获取app缓存大小

• (CGFloat)getCachSize {

  NSUInteger imageCacheSize = [[SDImageCache sharedImageCache] getSize];
  //获取自定义缓存大小
  //用枚举器遍历 一个文件夹的内容
  //1.获取 文件夹枚举器
  NSString *myCachePath = [NSHomeDirectory() stringByAppendingPathComponent:@"Library/Caches"];
  NSDirectoryEnumerator *enumerator = [[NSFileManager defaultManager] enumeratorAtPath:myCachePath];
  __block NSUInteger count = 0;
  //2.遍历
  for (NSString *fileName in enumerator) {
  NSString *path = [myCachePath stringByAppendingPathComponent:fileName];
  NSDictionary *fileDict = [[NSFileManager defaultManager] attributesOfItemAtPath:path error:nil];
  count += fileDict.fileSize;//自定义所有缓存大小
  }
  // 得到是字节 转化为M
  CGFloat totalSize = ((CGFloat)imageCacheSize+count)/1024/1024;
  return totalSize;
  }

43、清理app缓存

• (void)handleClearView {
  //删除两部分
  //1.删除 sd 图片缓存
  //先清除内存中的图片缓存
  [[SDImageCache sharedImageCache] clearMemory];
  //清除磁盘的缓存
  [[SDImageCache sharedImageCache] clearDisk];
  //2.删除自己缓存
  NSString *myCachePath = [NSHomeDirectory() stringByAppendingPathComponent:@"Library/Caches"];
  [[NSFileManager defaultManager] removeItemAtPath:myCachePath error:nil];
  }

44、模型转字典

static NSSet *classes;

• (NSMutableDictionary *)getParameterDictionary {

  NSMutableDictionary *dict = [NSMutableDictionary dictionary];

  Class c = self.class;

  while (c) {
  unsigned count;
  objc_property_t *properties = class_copyPropertyList([c class], &count);

    for (int i = 0; i < count; i++) {
        NSString *key = [NSString stringWithUTF8String:property_getName(properties[i])];
        dict[key] = [self valueForKey:key];
    }
    free(properties);
  
    // 获得父类
    c = class_getSuperclass(c);
  
    if ([self isClassFromFoundation:c]) break;
  

  }
  return dict;
  }

• (BOOL)isClassFromFoundation:(Class)c
  {
  if (c == [NSObject class] || c == [NSManagedObject class]) return YES;

  __block BOOL result = NO;
  [[self foundationClasses] enumerateObjectsUsingBlock:^(Class foundationClass, BOOL *stop) {
  if ([c isSubclassOfClass:foundationClass]) {
  result = YES;
  *stop = YES;
  }
  }];
  return result;
  }

• (NSSet *)foundationClasses
  {
  if (classes == nil) {
  // 集合中没有NSObject，因为几乎所有的类都是继承自NSObject，具体是不是NSObject需要特殊判断
  classes = [NSSet setWithObjects:
  [NSURL class],
  [NSDate class],
  [NSValue class],
  [NSData class],
  [NSError class],
  [NSArray class],
  [NSDictionary class],
  [NSString class],
  [NSAttributedString class], nil];
  }
  return classes;
  }

45、交换两个方法实现

Class aClass = [self class];

    SEL originalSelector = @selector(viewWillAppear:); 
    SEL swizzledSelector = @selector(xxx_viewWillAppear:); 

    Method originalMethod = class_getInstanceMethod(aClass, originalSelector); 
    Method swizzledMethod = class_getInstanceMethod(aClass, swizzledSelector); 

    BOOL didAddMethod = 
        class_addMethod(aClass, 
            originalSelector, 
            method_getImplementation(swizzledMethod), 
            method_getTypeEncoding(swizzledMethod)); 

    if (didAddMethod) { 
        class_replaceMethod(aClass, 
            swizzledSelector, 
            method_getImplementation(originalMethod), 
            method_getTypeEncoding(originalMethod)); 
    } else { 
        method_exchangeImplementations(originalMethod, swizzledMethod); 
    }

46、打印百分号和引号

NSLog(@"%%");
NSLog(@"\"");

47、几个常用权限判断

if ([CLLocationManager authorizationStatus] ==kCLAuthorizationStatusDenied) {
    NSLog(@"没有定位权限");
}
AVAuthorizationStatus statusVideo = [AVCaptureDevice authorizationStatusForMediaType:AVMediaTypeVideo];
if (statusVideo == AVAuthorizationStatusDenied) {
    NSLog(@"没有摄像头权限");
}
//是否有麦克风权限
AVAuthorizationStatus statusAudio = [AVCaptureDevice authorizationStatusForMediaType:AVMediaTypeAudio];
if (statusAudio == AVAuthorizationStatusDenied) {
    NSLog(@"没有录音权限");
}
[PHPhotoLibrary requestAuthorization:^(PHAuthorizationStatus status) {
    if (status == PHAuthorizationStatusDenied) {
        NSLog(@"没有相册权限");
    }
}];

48、获取手机型号

+ (NSString *)getDeviceInfo {
struct utsname systemInfo;
uname(&systemInfo);
NSString *platform = [NSString stringWithCString:systemInfo.machine encoding:NSASCIIStringEncoding];
if ([platform isEqualToString:@"iPhone1,1"]) return @"iPhone 2G";
if ([platform isEqualToString:@"iPhone1,2"]) return @"iPhone 3G";
if ([platform isEqualToString:@"iPhone2,1"]) return @"iPhone 3GS";
if ([platform isEqualToString:@"iPhone3,1"]) return @"iPhone 4";
if ([platform isEqualToString:@"iPhone3,2"]) return @"iPhone 4";
if ([platform isEqualToString:@"iPhone3,3"]) return @"iPhone 4";
if ([platform isEqualToString:@"iPhone4,1"]) return @"iPhone 4S";
if ([platform isEqualToString:@"iPhone5,1"]) return @"iPhone 5";
if ([platform isEqualToString:@"iPhone5,2"]) return @"iPhone 5";
if ([platform isEqualToString:@"iPhone5,3"]) return @"iPhone 5c";
if ([platform isEqualToString:@"iPhone5,4"]) return @"iPhone 5c";
if ([platform isEqualToString:@"iPhone6,1"]) return @"iPhone 5s";
if ([platform isEqualToString:@"iPhone6,2"]) return @"iPhone 5s";
if ([platform isEqualToString:@"iPhone7,1"]) return @"iPhone 6 Plus";
if ([platform isEqualToString:@"iPhone7,2"]) return @"iPhone 6";
if ([platform isEqualToString:@"iPhone8,1"]) return @"iPhone 6s";
if ([platform isEqualToString:@"iPhone8,2"]) return @"iPhone 6s Plus";
// 日行两款手机型号均为日本独占，可能使用索尼FeliCa支付方案而不是苹果支付
if ([platform isEqualToString:@"iPhone9,1"])    return @"国行、日版、港行iPhone 7";
if ([platform isEqualToString:@"iPhone9,2"])    return @"港行、国行iPhone 7 Plus";
if ([platform isEqualToString:@"iPhone9,3"])    return @"美版、台版iPhone 7";
if ([platform isEqualToString:@"iPhone9,4"])    return @"美版、台版iPhone 7 Plus";
if ([platform isEqualToString:@"iPhone8,4"]) return @"iPhone SE";
if ([platform isEqualToString:@"iPod1,1"]) return @"iPod Touch 1G";
if ([platform isEqualToString:@"iPod2,1"]) return @"iPod Touch 2G";
if ([platform isEqualToString:@"iPod3,1"]) return @"iPod Touch 3G";
if ([platform isEqualToString:@"iPod4,1"]) return @"iPod Touch 4G";
if ([platform isEqualToString:@"iPod5,1"]) return @"iPod Touch 5G";
if ([platform isEqualToString:@"iPad1,1"]) return @"iPad 1G";
if ([platform isEqualToString:@"iPad2,1"]) return @"iPad 2";
if ([platform isEqualToString:@"iPad2,2"]) return @"iPad 2";
if ([platform isEqualToString:@"iPad2,3"]) return @"iPad 2";
if ([platform isEqualToString:@"iPad2,4"]) return @"iPad 2";
if ([platform isEqualToString:@"iPad2,5"]) return @"iPad Mini 1G";
if ([platform isEqualToString:@"iPad2,6"]) return @"iPad Mini 1G";
if ([platform isEqualToString:@"iPad2,7"]) return @"iPad Mini 1G";
if ([platform isEqualToString:@"iPad3,1"]) return @"iPad 3";
if ([platform isEqualToString:@"iPad3,2"]) return @"iPad 3";
if ([platform isEqualToString:@"iPad3,3"]) return @"iPad 3";
if ([platform isEqualToString:@"iPad3,4"]) return @"iPad 4";
if ([platform isEqualToString:@"iPad3,5"]) return @"iPad 4";
if ([platform isEqualToString:@"iPad3,6"]) return @"iPad 4";
if ([platform isEqualToString:@"iPad4,1"]) return @"iPad Air";
if ([platform isEqualToString:@"iPad4,2"]) return @"iPad Air";
if ([platform isEqualToString:@"iPad4,3"]) return @"iPad Air";
if ([platform isEqualToString:@"iPad4,4"]) return @"iPad Mini 2G";
if ([platform isEqualToString:@"iPad4,5"]) return @"iPad Mini 2G";
if ([platform isEqualToString:@"iPad4,6"]) return @"iPad Mini 2G";
if ([platform isEqualToString:@"i386"]) return @"iPhone Simulator";
if ([platform isEqualToString:@"x86_64"]) return @"iPhone Simulator";
return platform;

}

49、长按复制功能

• (void)viewDidLoad
  {
  [self.view addGestureRecognizer:[[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(pasteBoard:)]];
  }
• (void)pasteBoard:(UILongPressGestureRecognizer *)longPress {
  if (longPress.state == UIGestureRecognizerStateBegan) {
  UIPasteboard *pasteboard = [UIPasteboard generalPasteboard];
  pasteboard.string = @"需要复制的文本";
  }
  }

50、cocoapods升级

在终端执行 sudo gem install -n / usr / local / bin cocoapods --pre

51、设置启动页后，依然显示之前的

删除app，手机重启，重新安装

52、判断图片类型

//通过图片Data数据第一个字节 来获取图片扩展名

• (NSString *)contentTypeForImageData:(NSData *)data
  {
  uint8_t c;
  [data getBytes:&c length:1];
  switch (c)
  {
  case 0xFF:
  return @"jpeg";

    case 0x89:
        return @"png";
  
    case 0x47:
        return @"gif";
  
    case 0x49:
    case 0x4D:
        return @"tiff";
  
    case 0x52:
    if ([data length] < 12) {
        return nil;
    }
  
    NSString *testString = [[NSString alloc] initWithData:[data subdataWithRange:NSMakeRange(0, 12)] encoding:NSASCIIStringEncoding];
    if ([testString hasPrefix:@"RIFF"]
        && [testString hasSuffix:@"WEBP"])
    {
        return @"webp";
    }
  
    return nil;
  

  }

  return nil;
  }

53、获取手机和app信息

NSDictionary *infoDictionary = [[NSBundle mainBundle] infoDictionary];
CFShow(infoDictionary);
// app名称
NSString *app_Name = [infoDictionary objectForKey:@"CFBundleDisplayName"];
// app版本
NSString *app_Version = [infoDictionary objectForKey:@"CFBundleShortVersionString"];
// app build版本
NSString *app_build = [infoDictionary objectForKey:@"CFBundleVersion"];

//手机序列号  
NSString* identifierNumber = [[UIDevice currentDevice] uniqueIdentifier];  
NSLog(@"手机序列号: %@",identifierNumber);  
//手机别名： 用户定义的名称  
NSString* userPhoneName = [[UIDevice currentDevice] name];  
NSLog(@"手机别名: %@", userPhoneName);  
//设备名称  
NSString* deviceName = [[UIDevice currentDevice] systemName];  
NSLog(@"设备名称: %@",deviceName );  
//手机系统版本  
NSString* phoneVersion = [[UIDevice currentDevice] systemVersion];  
NSLog(@"手机系统版本: %@", phoneVersion);  
//手机型号  
NSString* phoneModel = [[UIDevice currentDevice] model];  
NSLog(@"手机型号: %@",phoneModel );  
//地方型号  （国际化区域名称）  
NSString* localPhoneModel = [[UIDevice currentDevice] localizedModel];  
NSLog(@"国际化区域名称: %@",localPhoneModel );  

NSDictionary *infoDictionary = [[NSBundle mainBundle] infoDictionary];  
// 当前应用名称  
NSString *appCurName = [infoDictionary objectForKey:@"CFBundleDisplayName"];  
NSLog(@"当前应用名称：%@",appCurName);  
// 当前应用软件版本  比如：1.0.1  
NSString *appCurVersion = [infoDictionary objectForKey:@"CFBundleShortVersionString"];  
NSLog(@"当前应用软件版本:%@",appCurVersion);  
// 当前应用版本号码   int类型  
NSString *appCurVersionNum = [infoDictionary objectForKey:@"CFBundleVersion"];  
NSLog(@"当前应用版本号码：%@",appCurVersionNum);

54、获取一个类的所有属性

id LenderClass = objc_getClass("Lender");
unsigned int outCount, i;
objc_property_t *properties = class_copyPropertyList(LenderClass, &outCount);
for (i = 0; i < outCount; i++) {
objc_property_t property = properties[i];
fprintf(stdout, "%s %s\n", property_getName(property), property_getAttributes(property));
}

55、image圆角

• (UIImage *)circleImage
  {
  // NO代表透明
  UIGraphicsBeginImageContextWithOptions(self.size, NO, 1);
  // 获得上下文
  CGContextRef ctx = UIGraphicsGetCurrentContext();
  // 添加一个圆
  CGRect rect = CGRectMake(0, 0, self.size.width, self.size.height);
  // 方形变圆形
  CGContextAddEllipseInRect(ctx, rect);
  // 裁剪
  CGContextClip(ctx);
  // 将图片画上去
  [self drawInRect:rect];
  UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
  UIGraphicsEndImageContext();
  return image;
  }

56、image拉伸

• (UIImage *)resizableImage:(NSString *)imageName
  {
  UIImage *image = [UIImage imageNamed:imageName];
  CGFloat imageW = image.size.width;
  CGFloat imageH = image.size.height;
  return [image resizableImageWithCapInsets:UIEdgeInsetsMake(imageH * 0.5, imageW * 0.5, imageH * 0.5, imageW * 0.5) resizingMode:UIImageResizingModeStretch];
  }

57、JSON字符串转字典

• (NSDictionary *)parseJSONStringToNSDictionary:(NSString *)JSONString {
  NSData *JSONData = [JSONString dataUsingEncoding:NSUTF8StringEncoding];
  NSDictionary *responseJSON = [NSJSONSerialization JSONObjectWithData:JSONData options:NSJSONReadingMutableLeaves error:nil];
  return responseJSON;
  }

58、身份证号验证

• (BOOL)validateIdentityCard {
  BOOL flag;
  if (self.length <= 0) {
  flag = NO;
  return flag;
  }
  NSString *regex2 = @"^(\d{14}|\d{17})(\d|[xX])$";
  NSPredicate *identityCardPredicate = [NSPredicate predicateWithFormat:@"SELF MATCHES %@",regex2];
  return [identityCardPredicate evaluateWithObject:self];
  }

59、获取设备mac地址

• (NSString *)macAddress {
  int mib[6];
  size_t len;
  char *buf;
  unsigned char *ptr;
  struct if_msghdr *ifm;
  struct sockaddr_dl *sdl;

  mib[0] = CTL_NET;
  mib[1] = AF_ROUTE;
  mib[2] = 0;
  mib[3] = AF_LINK;
  mib[4] = NET_RT_IFLIST;

  if((mib[5] = if_nametoindex("en0")) == 0) {
  printf("Error: if_nametoindex error\n");
  return NULL;
  }

  if(sysctl(mib, 6, NULL, &len, NULL, 0) < 0) {
  printf("Error: sysctl, take 1\n");
  return NULL;
  }

  if((buf = malloc(len)) == NULL) {
  printf("Could not allocate memory. Rrror!\n");
  return NULL;
  }

  if(sysctl(mib, 6, buf, &len, NULL, 0) < 0) {
  printf("Error: sysctl, take 2");
  return NULL;
  }

  ifm = (struct if_msghdr *)buf;
  sdl = (struct sockaddr_dl *)(ifm + 1);
  ptr = (unsigned char *)LLADDR(sdl);
  NSString *outstring = [NSString stringWithFormat:@"%02X:%02X:%02X:%02X:%02X:%02X",
  *ptr, *(ptr+1), *(ptr+2), *(ptr+3), *(ptr+4), *(ptr+5)];
  free(buf);

  return outstring;
  }

60、导入自定义字体库

1、找到你想用的字体的 ttf 格式，拖入工程
2、在工程的plist中增加一行数组，“Fonts provided by application”
3、为这个key添加一个item，value为你刚才导入的ttf文件名
4、直接使用即可：label.font = [UIFont fontWithName:@"你刚才导入的ttf文件名" size:20.0]；

61、拿到当前正在显示的控制器，不管是push进去的，还是present进去的都能拿到

• (UIViewController )getVisibleViewControllerFrom:(UIViewController)vc {
  if ([vc isKindOfClass:[UINavigationController class]]) {
  return [self getVisibleViewControllerFrom:[((UINavigationController) vc) visibleViewController]];
  }else if ([vc isKindOfClass:[UITabBarController class]]){
  return [self getVisibleViewControllerFrom:[((UITabBarController) vc) selectedViewController]];
  } else {
  if (vc.presentedViewController) {
  return [self getVisibleViewControllerFrom:vc.presentedViewController];
  } else {
  return vc;
  }
  }
  }

62、runtime为一个类动态添加属性

// 动态添加属性的本质是: 让对象的某个属性与值产生关联
objc_setAssociatedObject(self, WZBPlaceholderViewKey, placeholderView, OBJC_ASSOCIATION_RETAIN_NONATOMIC);

63、获取runtime为一个类动态添加的属性

objc_getAssociatedObject(self, WZBPlaceholderViewKey);

64、KVO监听某个对象的属性

// 添加监听者
[self addObserver:self forKeyPath:property options:NSKeyValueObservingOptionNew context:nil];

// 当监听的属性值变化的时候会来到这个方法

• (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context {
  if ([keyPath isEqualToString:@"property"]) {
  [self textViewTextChange];
  } else {
  }
  }

65、Reachability判断网络状态

NetworkStatus status = [[Reachability reachabilityForInternetConnection] currentReachabilityStatus];
if (status == NotReachable) {
NSLog(@"当前设备无网络");
}
if (status == ReachableViaWiFi) {
NSLog(@"当前wifi网络");
}
if (status == ReachableViaWWAN) {
NSLog(@"当前蜂窝移动网络");
}