iOS小技巧总结(持续更新)
2016-09-06 17:37
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UITableView的Group样式下顶部空白处理
//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
- (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
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
#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
- (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
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
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
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
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 true killall Finder
隐藏
defaults write com.apple.finder AppleShowAllFiles -bool false killall Finder
iOS跳转到App Store下载应用评分
[[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
+ (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; }
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; } }
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]; }
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; }
iOS在当前屏幕获取第一响应
UIWindow * keyWindow = [[UIApplication sharedApplication] keyWindow]; UIView * firstResponder = [keyWindow performSelector:@selector(firstResponder)];
判断对象是否遵循了某协议
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
BOOL isView = [textView isDescendantOfView:self.view];
NSArray 快速求总和 最大值 最小值 和 平均值
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
[textField setValue:[UIColor redColor] forKeyPath:@"_placeholderLabel.textColor"];
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
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; }
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"); }
取消UICollectionView的隐式动画
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)。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
打开终端输入三条命令:touch ~/.lldbinit echo display @import UIKit >> ~/.lldbinit echo target stop-hook add -o \"target stop-hook disable\" >> ~/.lldbinit
CocoaPods pod install/pod update更新慢的问题
pod install --verbose --no-repo-update pod 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
UIImage *image = [UIImage imageNamed:@"aa"]; NSUInteger size = CGImageGetHeight(image.CGImage) * CGImageGetBytesPerRow(image.CGImage);
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);
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:NSStringDrawingUsesLineFragmentOrigin attributes:@{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
- (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
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