1、工作中常用小技巧

• 1、UITableView的Plain样式下底部多余行处理

  关键代码
    //高度可自调
    UIView *vi = [[UIView alloc] initWithFrame:CGRectMake(0, 0, kScreen_Width, kScreen_Height)];
    vi.backgroundColor = [UIColor whiteColor]; //颜色也可调，最好还是按照软件主题色调来选
    self.tableView.tableFooterView = vi; 

• 2 、获取某个View所在的控制器

- (UIViewController *)viewController
{
     UIViewController *viewController = nil;  
     UIResponder *next = self.nextResponder;
     while (next)
    {
          if ([next isKindOfClass:[UIViewController class]])
        {
              viewController = (UIViewController *)next;      
              break;    
        }    
        next = next.nextResponder;  
   } 
    return viewController;
}

• 3、清空NSUserDefaults所有记录

//方法一
NSString *appDomain = [[NSBundle mainBundle] bundleIdentifier];
[[NSUserDefaults standardUserDefaults] removePersistentDomainForName:appDomain];


//方法二
- (void)resetDefaults
{
    NSUserDefaults * defs = [NSUserDefaults standardUserDefaults];
    NSDictionary * dict = [defs dictionaryRepresentation];
    for (id key in dict)
    {
        [defs removeObjectForKey:key];
    }
    [defs synchronize];
}

• 4、打印系统所有已注册的字体名称

#pragma mark - 打印系统所有已注册的字体名称
void enumerateFonts()
{
    for(NSString *familyName in [UIFont familyNames])
   {
        NSLog(@"%@",familyName);               
        NSArray *fontNames = [UIFont fontNamesForFamilyName:familyName];       
        for(NSString *fontName in fontNames)
       {
            NSLog(@"\t|- %@",fontName);
       }
   }
}

• 5、获取图片某一点的颜色

- (UIColor*) getPixelColorAtLocation:(CGPoint)point inImage:(UIImage *)image
{

    UIColor* color = nil;
    CGImageRef inImage = image.CGImage;
    CGContextRef cgctx = [self createARGBBitmapContextFromImage:inImage];

    if (cgctx == NULL)
    {
        return nil; /* error */
    }
    size_t w = CGImageGetWidth(inImage);
    size_t h = CGImageGetHeight(inImage);
    CGRect rect = {{0,0},{w,h}};
    CGContextDrawImage(cgctx, rect, inImage);
    unsigned char* data = CGBitmapContextGetData (cgctx);
    if (data != NULL) 
    {
        int offset = 4*((w*round(point.y))+round(point.x));
        int alpha =  data[offset];
        int red = data[offset+1];
        int green = data[offset+2];
        int blue = data[offset+3];
        color = [UIColor colorWithRed:(red/255.0f) green:(green/255.0f) blue:
                 (blue/255.0f) alpha:(alpha/255.0f)];
    }
    CGContextRelease(cgctx);
    if (data) 
    {
        free(data);
    }
    return color;
}

• 6 、字符串反转

第一种：
- (NSString *)reverseWordsInString:(NSString *)str
{    
    NSMutableString *newString = [[NSMutableString alloc] initWithCapacity:str.length];
    for (NSInteger i = str.length - 1; i >= 0 ; i --)
    {
        unichar ch = [str characterAtIndex:i];       
        [newString appendFormat:@"%c", ch];    
    }    
     return newString;
}

//第二种：
- (NSString*)reverseWordsInString:(NSString*)str
{    
     NSMutableString *reverString = [NSMutableString stringWithCapacity:str.length];    
     [str enumerateSubstringsInRange:NSMakeRange(0, str.length) options:NSStringEnumerationReverse | NSStringEnumerationByComposedCharacterSequences  usingBlock:^(NSString *substring, NSRange substringRange, NSRange enclosingRange, BOOL *stop) { 
          [reverString appendString:substring];                         
      }];    
     return reverString;
}

• 7、禁止锁屏

默认情况下，当设备一段时间没有触控动作时，iOS会锁住屏幕。但有一些应用是不需要锁屏的，比如视频播放器。

[UIApplication sharedApplication].idleTimerDisabled = YES; 或
[[UIApplication sharedApplication] setIdleTimerDisabled:YES];

• 8、模态推出透明界面

 UIViewController *vc = [[UIViewController alloc] init];
UINavigationController *na = [[UINavigationController alloc] initWithRootViewController:vc];

if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 8.0)
{
     na.modalPresentationStyle = UIModalPresentationOverCurrentContext;
}
else
{
     self.modalPresentationStyle = UIModalPresentationCurrentContext;
}

[self presentViewController:na animated:YES completion:nil];

• 9、字符串按多个符号分割

 //原始字符串
    NSString *str = @"abc,veh.lslsl,eee";
    NSCharacterSet *set = [NSCharacterSet characterSetWithCharactersInString:@",."]; //"分割的字符串是",.""
    NSArray *arr = [str componentsSeparatedByCharactersInSet:set];
    [arr enumerateObjectsUsingBlock:^(NSString  * obj, NSUInteger idx, BOOL * _Nonnull stop) {
        NSLog(@" obj -- %@",obj);
        //打印如下
//         obj -- abc
//         obj -- veh
//         obj -- lslsl
//         obj -- eee
    }];

• 10、iOS应用跳转到指定URL

  NSURL *url = [NSURL URLWithString:@"您APP在应用商店的地址"];

    //iOS 10以前
    //    [[UIApplication sharedApplication] openURL:url];

    //iOS10之后
    NSDictionary *dict = @{@"key":@"value"}; //用于对象间通信
    [[UIApplication sharedApplication] openURL:url options:dict completionHandler:^(BOOL success) {
        //打开成功之后会回到主线程
        NSLog(@"当前线程 ... %@",[NSThread currentThread]);
    }];

• 11、iOS 获取汉字的拼音

 - (NSString *)transform:(NSString *)chinese
{
    //将NSString装换成NSMutableString
    NSMutableString *pinyin = [chinese mutableCopy];
    //将汉字转换为拼音(带音标)
    CFStringTransform((__bridge CFMutableStringRef)pinyin, NULL, kCFStringTransformMandarinLatin, NO);

    NSLog(@"%@", pinyin);
    //去掉拼音的音标
    CFStringTransform((__bridge CFMutableStringRef)pinyin, NULL, kCFStringTransformStripCombiningMarks, NO);
    NSLog(@"%@", pinyin);
    //返回最近结果
    return pinyin;
}

• 12 、手动更改iOS状态栏的颜色

- (void)setStatusBarBackgroundColor:(UIColor *)color
{
    UIView *statusBar = [[[UIApplication sharedApplication] valueForKey:@"statusBarWindow"] valueForKey:@"statusBar"];

    if ([statusBar respondsToSelector:@selector(setBackgroundColor:)])
    {
        statusBar.backgroundColor = color;    
    }
}

• 13 、判断当前ViewController是push还是present的方式显示的

NSArray *viewcontrollers = self.navigationController.viewControllers;
if (viewcontrollers.count > 1)
{
    if ([viewcontrollers objectAtIndex:viewcontrollers.count - 1] == self)
    {
        //push方式
       [self.navigationController popViewControllerAnimated:YES];
    }
}
else
{
    //present方式
    [self dismissViewControllerAnimated:YES completion:nil];
}

• 14 、获取实际使用的LaunchImage图片

- (NSString *)getLaunchImageName
{
    CGSize viewSize = self.window.bounds.size;
    // 竖屏    
    NSString *viewOrientation = @"Portrait";  
    NSString *launchImageName = nil;    
    NSArray* imagesDict = [[[NSBundle mainBundle] infoDictionary] valueForKey:@"UILaunchImages"];
    for (NSDictionary* dict in imagesDict)
    {
        CGSize imageSize = CGSizeFromString(dict[@"UILaunchImageSize"]);
        if (CGSizeEqualToSize(imageSize, viewSize) && [viewOrientation isEqualToString:dict[@"UILaunchImageOrientation"]])
        {
            launchImageName = dict[@"UILaunchImageName"];        
        }    
    }    
    return launchImageName;
}

• 15 、iOS在当前屏幕获取第一响应

UIWindow * keyWindow = [[UIApplication sharedApplication] keyWindow];
UIView * firstResponder = [keyWindow performSelector:@selector(firstResponder)];

• 16 、判断对象是否遵循了某协议

if ([self.selectedController conformsToProtocol:@protocol(RefreshPtotocol)])
{
    [self.selectedController performSelector:@selector(onTriggerRefresh)];
}

• 17 、判断view是不是指定视图的子视图

BOOL isView = [textView isDescendantOfView:self.view];

• 18 、修改UITextField中Placeholder的文字颜色

[textField setValue:[UIColor redColor] forKeyPath:@"_placeholderLabel.textColor"];

• 19 、关于NSDateFormatter的格式

G: 公元时代，例如AD公元
yy: 年的后2位
yyyy: 完整年
MM: 月，显示为1-12
MMM: 月，显示为英文月份简写,如 Jan
MMMM: 月，显示为英文月份全称，如 Janualy
dd: 日，2位数表示，如02
d: 日，1-2位显示，如 2
EEE: 简写星期几，如Sun
EEEE: 全写星期几，如Sunday
aa: 上下午，AM/PM
H: 时，24小时制，0-23
K：时，12小时制，0-11
m: 分，1-2位
mm: 分，2位
s: 秒，1-2位
ss: 秒，2位
S: 毫秒

• 20 、获取一个类的所有子类

+ (NSArray *) allSubclasses
{
    Class myClass = [self class];
    NSMutableArray *mySubclasses = [NSMutableArray array];
    unsigned int numOfClasses;
    Class *classes = objc_copyClassList(&numOfClasses;);
    for (unsigned int ci = 0; ci < numOfClasses; ci++)
    {
        Class superClass = classes[ci];
        do{
            superClass = class_getSuperclass(superClass);
        } while (superClass && superClass != myClass);

        if (superClass)
        {
            [mySubclasses addObject: classes[ci]];
        }
    }
    free(classes);
    return mySubclasses;
}

• 21、监测IOS设备是否设置了代理，需要CFNetwork.framework

NSDictionary *proxySettings = (__bridge NSDictionary *)(CFNetworkCopySystemProxySettings());
NSArray *proxies = (__bridge NSArray *)(CFNetworkCopyProxiesForURL((__bridge CFURLRef _Nonnull)([NSURL URLWithString:@"http://www.baidu.com"]), (__bridge CFDictionaryRef _Nonnull)(proxySettings)));
NSLog(@"\n%@",proxies);

NSDictionary *settings = proxies[0];
NSLog(@"%@",[settings objectForKey:(NSString *)kCFProxyHostNameKey]);
NSLog(@"%@",[settings objectForKey:(NSString *)kCFProxyPortNumberKey]);
NSLog(@"%@",[settings objectForKey:(NSString *)kCFProxyTypeKey]);

if ([[settings objectForKey:(NSString *)kCFProxyTypeKey] isEqualToString:@"kCFProxyTypeNone"])
{
    NSLog(@"没代理");
}
else
{
    NSLog(@"设置了代理");
}

• 22、阿拉伯数字转中文格式

  
+(NSString *)translation:(NSString *)arebic
{
    NSString *str = arebic;
    NSArray *arabic_numerals = @[@"1",@"2",@"3",@"4",@"5",@"6",@"7",@"8",@"9",@"0"];
    NSArray *chinese_numerals = @[@"一",@"二",@"三",@"四",@"五",@"六",@"七",@"八",@"九",@"零"];
    NSArray *digits = @[@"个",@"十",@"百",@"千",@"万",@"十",@"百",@"千",@"亿",@"十",@"百",@"千",@"兆"];
    NSDictionary *dictionary = [NSDictionary dictionaryWithObjects:chinese_numerals forKeys:arabic_numerals];

    NSMutableArray *sums = [NSMutableArray array];
    for (int i = 0; i < str.length; i ++) {
        NSString *substr = [str substringWithRange:NSMakeRange(i, 1)];
        NSString *a = [dictionary objectForKey:substr];
        NSString *b = digits[str.length -i-1];
        NSString *sum = [a stringByAppendingString:b];
        if ([a isEqualToString:chinese_numerals[9]])
        {
            if([b isEqualToString:digits[4]] || [b isEqualToString:digits[8]])
            {
                sum = b;
                if ([[sums lastObject] isEqualToString:chinese_numerals[9]])
                {
                    [sums removeLastObject];
                }
            }else
            {
                sum = chinese_numerals[9];
            }

            if ([[sums lastObject] isEqualToString:sum])
            {
                continue;
            }
        }

        [sums addObject:sum];
    }

    NSString *sumStr = [sums componentsJoinedByString:@""];
    NSString *chinese = [sumStr substringToIndex:sumStr.length-1];
    NSLog(@"%@",str);
    NSLog(@"%@",chinese);
    return chinese;
}  

• 23 、取消UICollectionView的隐式动画

下面几种方法都可以帮你去除这些动画

UICollectionView在reloadItems的时候，默认会附加一个隐式的fade动画，有时候很讨厌，尤其是当你的cell是复合cell的情况下(比如cell使用到了UIStackView)。

//方法一
[UIView performWithoutAnimation:^{
    [collectionView reloadItemsAtIndexPaths:@[[NSIndexPath indexPathForItem:index inSection:0]]];
}];

//方法二
[UIView animateWithDuration:0 animations:^{
    [collectionView performBatchUpdates:^{
        [collectionView reloadItemsAtIndexPaths:@[[NSIndexPath indexPathForItem:index inSection:0]]];
    } completion:nil];
}];

//方法三
[UIView setAnimationsEnabled:NO];
[self.trackPanel performBatchUpdates:^{
    [collectionView reloadItemsAtIndexPaths:@[[NSIndexPath indexPathForItem:index inSection:0]]];
} completion:^(BOOL finished) {
    [UIView setAnimationsEnabled:YES];
}];

• 24 、GCD timer定时器

dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
dispatch_source_t timer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0,queue);
dispatch_source_set_timer(timer,dispatch_walltime(NULL, 0),1.0*NSEC_PER_SEC, 0); //每秒执行
dispatch_source_set_event_handler(timer, ^{
    //@"倒计时结束，关闭"
    dispatch_source_cancel(timer);
    dispatch_async(dispatch_get_main_queue(), ^{

    });
});
dispatch_resume(timer);

• 25 、计算文件大小

//文件大小
- (long long)fileSizeAtPath:(NSString *)path
{
    NSFileManager *fileManager = [NSFileManager defaultManager];

    if ([fileManager fileExistsAtPath:path])
    {
        long long size = [fileManager attributesOfItemAtPath:path error:nil].fileSize;
        return size;
    }

    return 0;
}


//文件夹大小
- (long long)folderSizeAtPath:(NSString *)path
{
    NSFileManager *fileManager = [NSFileManager defaultManager];

    long long folderSize = 0;

    if ([fileManager fileExistsAtPath:path])
    {
        NSArray *childerFiles = [fileManager subpathsAtPath:path];
        for (NSString *fileName in childerFiles)
        {
            NSString *fileAbsolutePath = [path stringByAppendingPathComponent:fileName];
            if ([fileManager fileExistsAtPath:fileAbsolutePath])
            {
                long long size = [fileManager attributesOfItemAtPath:fileAbsolutePath error:nil].fileSize;
                folderSize += size;
            }
        }
    }

    return folderSize;
}

• 26 、UIView设置部分圆角

 你是不是也遇到过这样的问题，一个button或者label，只要右边的两个角圆角，或者只要一个圆角。该怎么办呢。这就需要图层蒙版来帮助我们了
CGRect rect = view.bounds;
CGSize radio = CGSizeMake(30, 30);//圆角尺寸
UIRectCorner corner = UIRectCornerTopLeft|UIRectCornerTopRight;//这只圆角位置
UIBezierPath *path = [UIBezierPath bezierPathWithRoundedRect:rect byRoundingCorners:corner cornerRadii:radio];
CAShapeLayer *masklayer = [[CAShapeLayer alloc]init];//创建shapelayer
masklayer.frame = view.bounds;
masklayer.path = path.CGPath;//设置路径
view.layer.mask = masklayer;  

• 27 、去掉导航栏返回的back标题

    [[UIBarButtonItem appearance] setBackButtonTitlePositionAdjustment:UIOffsetMake(0, -60)forBarMetrics:UIBarMetricsDefault];

• 28 、字符串中是否含有中文

+ (BOOL)checkIsChinese:(NSString *)string
{
    for (int i=0; i

• 29 、判断两个日期是否在同一周 写在NSDate的category里面

- (BOOL)isSameDateWithDate:(NSDate *)date
{
    //日期间隔大于七天之间返回NO
    if (fabs([self timeIntervalSinceDate:date]) >= 7 * 24 *3600)
    {
        return NO;
    }

    NSCalendar *calender = [NSCalendar currentCalendar];
    calender.firstWeekday = 2;//设置每周第一天从周一开始
    //计算两个日期分别为这年第几周
    NSUInteger countSelf = [calender ordinalityOfUnit:NSCalendarUnitWeekday inUnit:NSCalendarUnitYear forDate:self];
    NSUInteger countDate = [calender ordinalityOfUnit:NSCalendarUnitWeekday inUnit:NSCalendarUnitYear forDate:date];

    //相等就在同一周，不相等就不在同一周
    return countSelf == countDate;
}

• 30 、获取手机安装的应用

Class c =NSClassFromString(@"LSApplicationWorkspace");
id s = [(id)c performSelector:NSSelectorFromString(@"defaultWorkspace")];
NSArray *array = [s performSelector:NSSelectorFromString(@"allInstalledApplications")];
for (id item in array)
{
    NSLog(@"%@",[item performSelector:NSSelectorFromString(@"applicationIdentifier")]);
    //NSLog(@"%@",[item performSelector:NSSelectorFromString(@"bundleIdentifier")]);
    NSLog(@"%@",[item performSelector:NSSelectorFromString(@"bundleVersion")]);
    NSLog(@"%@",[item performSelector:NSSelectorFromString(@"shortVersionString")]);
}

• 31 、 navigationBar变为纯透明

//第一种方法
//导航栏纯透明
[self.navigationBar setBackgroundImage:[UIImage new] forBarMetrics:UIBarMetricsDefault];
//去掉导航栏底部的黑线
self.navigationBar.shadowImage = [UIImage new];

//第二种方法
[[self.navigationBar subviews] objectAtIndex:0].alpha = 0;

tabBar同理

[self.tabBar setBackgroundImage:[UIImage new]];
self.tabBar.shadowImage = [UIImage new];

• 32 、navigationBar根据滑动距离的渐变色实现

//第一种
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
    CGFloat offsetToShow = 200.0;//滑动多少就完全显示
    CGFloat alpha = 1 - (offsetToShow - scrollView.contentOffset.y) / offsetToShow;
    [[self.navigationController.navigationBar subviews] objectAtIndex:0].alpha = alpha;
}

//第二种
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
    CGFloat offsetToShow = 200.0;
    CGFloat alpha = 1 - (offsetToShow - scrollView.contentOffset.y) / offsetToShow;

    [self.navigationController.navigationBar setShadowImage:[UIImage new]];
    [self.navigationController.navigationBar setBackgroundImage:[self imageWithColor:[[UIColor orangeColor]colorWithAlphaComponent:alpha]] forBarMetrics:UIBarMetricsDefault];
}

• 33 //生成一张纯色的图片

- (UIImage *)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 *theImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    return theImage;
}

• 34 、相关路径

iOS 开发中一些相关的路径
模拟器的位置:
/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs
文档安装位置:
/Applications/Xcode.app/Contents/Developer/Documentation/DocSets
插件保存路径:
~/Library/ApplicationSupport/Developer/Shared/Xcode/Plug-ins
自定义代码段的保存路径:
~/Library/Developer/Xcode/UserData/CodeSnippets/
如果找不到CodeSnippets文件夹，可以自己新建一个CodeSnippets文件夹。
描述文件路径
~/Library/MobileDevice/Provisioning Profiles
navigationItem的BarButtonItem如何紧靠屏幕右边界或者左边界？