iOS小技巧总结(持续更新)

UITableView的Group样式下顶部空白处理

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//分组列表头部空白处理UIView *view = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 0, 0.1)];self.tableView.tableHeaderView = view;

获取某个view所在的控制器

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- (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;}

两种方法删除NSUserDefaults所有记录

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• 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];}

打印系统所有已注册的字体名称

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#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);}}}

获取图片某一点的颜色

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- (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;}

字符串反转

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• 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;}

禁止锁屏

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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];

模态推出透明界面

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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];

Xcode调试不显示内存占用

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editSCheme 里面有个选项叫叫做 enable zoombie Objects取消选中

显示隐藏文件

• 显示

defaults write com.apple.finder AppleShowAllFiles -bool truekillall Finder

• 隐藏

defaults write com.apple.finder AppleShowAllFiles -bool falsekillall Finder

iOS跳转到App Store下载应用评分

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[[UIApplication sharedApplication] openURL:[NSURL URLWithString:@"itms-apps://itunes.apple.com/WebObjects/MZStore.woa/wa/viewContentsUserReviews?type=Purple+Software&id=APPID"]];

iOS 获取汉字的拼音

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+ (NSString *)transform:(NSString *)chinese{//将NSString装换成NSMutableStringNSMutableString *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;}

手动更改iOS状态栏的颜色

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- (void)setStatusBarBackgroundColor:(UIColor *)color{UIView *statusBar = [[[UIApplication sharedApplication] valueForKey:@"statusBarWindow"] valueForKey:@"statusBar"];if ([statusBar respondsToSelector:@selector(setBackgroundColor:)]){statusBar.backgroundColor = color;}}

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

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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];}

获取实际使用的LaunchImage图片

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- (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;}

iOS在当前屏幕获取第一响应

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

判断对象是否遵循了某协议

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

判断view是不是指定视图的子视图

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

NSArray 快速求总和 最大值 最小值 和 平均值

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NSArray *array = [NSArray arrayWithObjects:@"2.0", @"2.3", @"3.0", @"4.0", @"10", nil];CGFloat sum = [[array valueForKeyPath:@"@sum.floatValue"] floatValue];CGFloat avg = [[array valueForKeyPath:@"@avg.floatValue"] floatValue];CGFloat max =[[array valueForKeyPath:@"@max.floatValue"] floatValue];CGFloat min =[[array valueForKeyPath:@"@min.floatValue"] floatValue];NSLog(@"%f\n%f\n%f\n%f",sum,avg,max,min);

修改UITextField中Placeholder的文字颜色

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

关于NSDateFormatter的格式

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• 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

获取一个类的所有子类

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+ (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;}

监测IOS设备是否设置了代理，需要CFNetwork.framework

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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");}

取消UICollectionView的隐式动画

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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)。

• 下面几种方法都可以帮你去除这些动画

  • 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];}];

让Xcode的控制台支持LLDB类型的打印

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• 打开终端输入三条命令:

touch ~/.lldbinitecho display @import UIKit >> ~/.lldbinitecho target stop-hook add -o \"target stop-hook disable\" >> ~/.lldbinit

CocoaPods pod install/pod update更新慢的问题

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pod install --verbose --no-repo-updatepod update --verbose --no-repo-update

如果不加后面的参数，默认会升级CocoaPods的spec仓库，加一个参数可以省略这一步，然后速度就会提升不少

UIImage 占用内存大小

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UIImage *image = [UIImage imageNamed:@"aa"];NSUInteger size  = CGImageGetHeight(image.CGImage) * CGImageGetBytesPerRow(image.CGImage);

GCD timer定时器

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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);

图片上绘制文字 写一个UIImage的category

- (UIImage *)imageWithTitle:(NSString *)title fontSize:(CGFloat)fontSize{//画布大小CGSize size=CGSizeMake(self.size.width,self.size.height);//创建一个基于位图的上下文UIGraphicsBeginImageContextWithOptions(size,NO,0.0);//opaque:NO  scale:0.0[self drawAtPoint:CGPointMake(0.0,0.0)];//文字居中显示在画布上NSMutableParagraphStyle* paragraphStyle = [[NSParagraphStyle defaultParagraphStyle] mutableCopy];paragraphStyle.lineBreakMode = NSLineBreakByCharWrapping;paragraphStyle.alignment=NSTextAlignmentCenter;//文字居中//计算文字所占的size,文字居中显示在画布上CGSize sizeText=[title boundingRectWithSize:self.size options:NSStringDrawingUsesLineFragmentOriginattributes:@{NSFontAttributeName:[UIFont systemFontOfSize:fontSize]}context:nil].size;CGFloat width = self.size.width;CGFloat height = self.size.height;CGRect rect = CGRectMake((width-sizeText.width)/2, (height-sizeText.height)/2, sizeText.width, sizeText.height);//绘制文字[title drawInRect:rect withAttributes:@{ NSFontAttributeName:[UIFont systemFontOfSize:fontSize],NSForegroundColorAttributeName:[ UIColor whiteColor],NSParagraphStyleAttributeName:paragraphStyle}];//返回绘制的新图形UIImage *newImage= UIGraphicsGetImageFromCurrentImageContext();UIGraphicsEndImageContext();return newImage;}

查找一个视图的所有子视图

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- (NSMutableArray *)allSubViewsForView:(UIView *)view{NSMutableArray *array = [NSMutableArray arrayWithCapacity:0];for (UIView *subView in view.subviews){[array addObject:subView];if (subView.subviews.count > 0){[array addObjectsFromArray:[self allSubViewsForView:subView]];}}return array;}

转自：简书作者

更新

iOS cell添加点击时改变字体的颜色及背景

  cell.selectedBackgroundView.backgroundColor = [UIColor whiteColor];//选中后变换，色彩的变换      cell.textLabel.highlightedTextColor = [UIColor whiteColor];//选中字体颜色cell.textLabel.textColor = [UIColor whiteColor];        cell.backgroundView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"cc"]];        cell.selectedBackgroundView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"cc_no"]];//选中后变换，图片的变换