iOS面试资料以及工作经验总结

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：1、xib的cell没有注册 2、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