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iOS 知识-常用小技巧大杂烩

iOS 知识-常用小技巧大杂烩


1,打印View所有子视图

 po [[self view]recursiveDescription]

2,layoutSubviews调用的调用时机

 * 当视图第一次显示的时候会被调用 * 当这个视图显示到屏幕上了,点击按钮 * 添加子视图也会调用这个方法 * 当本视图的大小发生改变的时候是会调用的 * 当子视图的frame发生改变的时候是会调用的 * 当删除子视图的时候是会调用的

3,NSString过滤特殊字符

 // 定义一个特殊字符的集合 NSCharacterSet *set = [NSCharacterSet characterSetWithCharactersInString: @"@/:;()¥「」"、[]{}#%-*+=_//|~<>$€^•'@#$%^&*()_+'/""]; // 过滤字符串的特殊字符 NSString *newString = [trimString stringByTrimmingCharactersInSet:set];

4,TransForm属性

 //平移按钮 CGAffineTransform transForm = self.buttonView.transform; self.buttonView.transform = CGAffineTransformTranslate(transForm, 10, 0);  //旋转按钮 CGAffineTransform transForm = self.buttonView.transform; self.buttonView.transform = CGAffineTransformRotate(transForm, M_PI_4);  //缩放按钮 self.buttonView.transform = CGAffineTransformScale(transForm, 1.2, 1.2);  //初始化复位 self.buttonView.transform = CGAffineTransformIdentity;

5,去掉分割线多余15像素

 首先在viewDidLoad方法加入以下代码:  if ([self.tableView respondsToSelector:@selector(setSeparatorInset:)]) {         [self.tableView setSeparatorInset:UIEdgeInsetsZero];     }     if ([self.tableView respondsToSelector:@selector(setLayoutMargins:)]) {                 [self.tableView setLayoutMargins:UIEdgeInsetsZero]; } 然后在重写willDisplayCell方法 - (void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell  forRowAtIndexPath:(NSIndexPath *)indexPath{        if ([cell respondsToSelector:@selector(setSeparatorInset:)]) {                     [cell setSeparatorInset:UIEdgeInsetsZero];         }         if ([cell respondsToSelector:@selector(setLayoutMargins:)]) {                      [cell setLayoutMargins:UIEdgeInsetsZero];         } }

6,计算方法耗时时间间隔

 // 获取时间间隔 #define TICK   CFAbsoluteTime start = CFAbsoluteTimeGetCurrent(); #define TOCK   NSLog(@"Time: %f", CFAbsoluteTimeGetCurrent() - start)

7,Color颜色宏定义

 // 随机颜色 #define RANDOM_COLOR [UIColor colorWithRed:arc4random_uniform(256) / 255.0 green:arc4random_uniform(256) / 255.0 blue:arc4random_uniform(256) / 255.0 alpha:1] // 颜色(RGB) #define RGBCOLOR(r, g, b) [UIColor colorWithRed:(r)/255.0f green:(g)/255.0f blue:(b)/255.0f alpha:1] #define RGBACOLOR(r, g, b, a) [UIColor colorWithRed:(r)/255.0f green:(g)/255.0f blue:(b)/255.0f alpha:(a)]

8,Alert提示宏定义

 #define Alert(_S_, ...) [[[UIAlertView alloc] initWithTitle:@"提示" message:[NSString stringWithFormat:(_S_), ##__VA_ARGS__] delegate:nil cancelButtonTitle:@"确定" otherButtonTitles:nil] show]

8,让 iOS 应用直接退出

 - (void)exitApplication {     AppDelegate *app = [UIApplication sharedApplication].delegate;     UIWindow *window = app.window;      [UIView animateWithDuration:1.0f animations:^{         window.alpha = 0;     } completion:^(BOOL finished) {         exit(0);     }]; }

8,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);

9,修改Label中不同文字颜色

 - (void)touchesEnded:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {     [self editStringColor:self.label.text editStr:@"好" color:[UIColor blueColor]]; }  - (void)editStringColor:(NSString *)string editStr:(NSString *)editStr color:(UIColor *)color {     // string为整体字符串, editStr为需要修改的字符串     NSRange range = [string rangeOfString:editStr];      NSMutableAttributedString *attribute = [[NSMutableAttributedString alloc] initWithString:string];      // 设置属性修改字体颜色UIColor与大小UIFont     [attribute addAttributes:@{NSForegroundColorAttributeName:color} range:range];      self.label.attributedText = attribute; }

10,播放声音

   #import<AVFoundation/AVFoundation.h>    //  1.获取音效资源的路径    NSString *path = [[NSBundle mainBundle]pathForResource:@"pour_milk" ofType:@"wav"];    //  2.将路劲转化为url    NSURL *tempUrl = [NSURL fileURLWithPath:path];    //  3.用转化成的url创建一个播放器    NSError *error = nil;    AVAudioPlayer *play = [[AVAudioPlayer alloc]initWithContentsOfURL:tempUrl error:&error];    self.player = play;    //  4.播放    [play play];

11,检测是否IPad Pro

 - (BOOL)isIpadPro {      UIScreen *Screen = [UIScreen mainScreen];      CGFloat width = Screen.nativeBounds.size.width/Screen.nativeScale;     CGFloat height = Screen.nativeBounds.size.height/Screen.nativeScale;            BOOL isIpad =[[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPad;      BOOL hasIPadProWidth = fabs(width - 1024.f) < DBL_EPSILON;       BOOL hasIPadProHeight = fabs(height - 1366.f) < DBL_EPSILON;     return isIpad && hasIPadProHeight && hasIPadProWidth; }

11,修改Tabbar Item的属性

     // 修改标题位置     self.tabBarItem.titlePositionAdjustment = UIOffsetMake(0, -10);     // 修改图片位置     self.tabBarItem.imageInsets = UIEdgeInsetsMake(-3, 0, 3, 0);      // 批量修改属性     for (UIBarItem *item in self.tabBarController.tabBar.items) {         [item setTitleTextAttributes:[NSDictionary dictionaryWithObjectsAndKeys:                  [UIFont fontWithName:@"Helvetica" size:19.0], NSFontAttributeName, nil]                             forState:UIControlStateNormal];     }      // 设置选中和未选中字体颜色     [[UITabBar appearance] setShadowImage:[[UIImage alloc] init]];      //未选中字体颜色     [[UITabBarItem appearance] setTitleTextAttributes:@{NSForegroundColorAttributeName:[UIColor greenColor]} forState:UIControlStateNormal];      //选中字体颜色     [[UITabBarItem appearance] setTitleTextAttributes:@{NSForegroundColorAttributeName:[UIColor cyanColor]} forState:UIControlStateSelected];

12,NULL - nil - Nil - NSNULL的区别

 * nil是OC的,空对象,地址指向空(0)的对象。对象的字面零值  * Nil是Objective-C类的字面零值  * NULL是C的,空地址,地址的数值是0,是个长整数  * NSNull用于解决向NSArray和NSDictionary等集合中添加空值的问题

11,去掉BackBarButtonItem的文字

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

12,控件不能交互的一些原因

 1,控件的userInteractionEnabled = NO 2,透明度小于等于0.01,aplpha 3,控件被隐藏的时候,hidden = YES 4,子视图的位置超出了父视图的有效范围,子视图无法交互,设置了

12,修改UITextField中Placeholder的文字颜色

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

13,视图的生命周期

 1、 alloc 创建对象,分配空间 2、 init (initWithNibName) 初始化对象,初始化数据 3、 loadView 从nib载入视图 ,除非你没有使用xib文件创建视图 4、 viewDidLoad 载入完成,可以进行自定义数据以及动态创建其他控件 5、 viewWillAppear视图将出现在屏幕之前,马上这个视图就会被展现在屏幕上了 6、 viewDidAppear 视图已在屏幕上渲染完成  1、viewWillDisappear 视图将被从屏幕上移除之前执行 2、viewDidDisappear 视图已经被从屏幕上移除,用户看不到这个视图了 3、dealloc 视图被销毁,此处需要对你在init和viewDidLoad中创建的对象进行释放.  viewVillUnload- 当内存过低,即将释放时调用; viewDidUnload-当内存过低,释放一些不需要的视图时调用。

14,应用程序的生命周期

 1,启动但还没进入状态保存 : - (BOOL)application:(UIApplication *)application willFinishLaunchingWithOptions:(NSDictionary *)launchOptions   2,基本完成程序准备开始运行: - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions  3,当应用程序将要入非活动状态执行,应用程序不接收消息或事件,比如来电话了: - (void)applicationWillResignActive:(UIApplication *)application   4,当应用程序入活动状态执行,这个刚好跟上面那个方法相反: - (void)applicationDidBecomeActive:(UIApplication *)application     5,当程序被推送到后台的时候调用。所以要设置后台继续运行,则在这个函数里面设置即可: - (void)applicationDidEnterBackground:(UIApplication *)application    6,当程序从后台将要重新回到前台时候调用,这个刚好跟上面的那个方法相反: - (void)applicationWillEnterForeground:(UIApplication *)application    7,当程序将要退出是被调用,通常是用来保存数据和一些退出前的清理工作: - (void)applicationWillTerminate:(UIApplication *)application

15,判断view是不是指定视图的子视图

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

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,页面强制横屏

 #pragma mark - 强制横屏代码 - (BOOL)shouldAutorotate{         //是否支持转屏            return NO; } - (UIInterfaceOrientationMask)supportedInterfaceOrientations{         //支持哪些转屏方向         return UIInterfaceOrientationMaskLandscape; } - (UIInterfaceOrientation)preferredInterfaceOrientationForPresentation{                    return UIInterfaceOrientationLandscapeRight; } - (BOOL)prefersStatusBarHidden{        return NO; }

18,系统键盘通知消息

 1、UIKeyboardWillShowNotification-将要弹出键盘 2、UIKeyboardDidShowNotification-显示键盘 3、UIKeyboardWillHideNotification-将要隐藏键盘 4、UIKeyboardDidHideNotification-键盘已经隐藏 5、UIKeyboardWillChangeFrameNotification-键盘将要改变frame 6、UIKeyboardDidChangeFrameNotification-键盘已经改变frame

19,关闭navigationController的滑动返回手势

 self.navigationController.interactivePopGestureRecognizer.enabled = NO;

20,设置状态栏为任意的颜色

 - (void)setStatusColor {     UIView *statusBarView = [[UIView alloc] initWithFrame:CGRectMake(0, 0,[UIScreen mainScreen].bounds.size.width, 20)];     statusBarView.backgroundColor = [UIColor orangeColor];     [self.view addSubview:statusBarView]; }

21,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

下次重新运行项目,然后就不报错了。

iOS 知识-常用小技巧大杂烩


22,Label行间距

 -(void)test{     NSMutableAttributedString *attributedString =        [[NSMutableAttributedString alloc] initWithString:self.contentLabel.text];     NSMutableParagraphStyle *paragraphStyle =  [[NSMutableParagraphStyle alloc] init];      [paragraphStyle setLineSpacing:3];      //调整行间距           [attributedString addAttribute:NSParagraphStyleAttributeName                           value:paragraphStyle                           range:NSMakeRange(0, [self.contentLabel.text length])];      self.contentLabel.attributedText = attributedString; }

23,UIImageView填充模式

 @"UIViewContentModeScaleToFill",      // 拉伸自适应填满整个视图   @"UIViewContentModeScaleAspectFit",   // 自适应比例大小显示   @"UIViewContentModeScaleAspectFill",  // 原始大小显示   @"UIViewContentModeRedraw",           // 尺寸改变时重绘   @"UIViewContentModeCenter",           // 中间   @"UIViewContentModeTop",              // 顶部   @"UIViewContentModeBottom",           // 底部   @"UIViewContentModeLeft",             // 中间贴左   @"UIViewContentModeRight",            // 中间贴右   @"UIViewContentModeTopLeft",          // 贴左上   @"UIViewContentModeTopRight",         // 贴右上   @"UIViewContentModeBottomLeft",       // 贴左下   @"UIViewContentModeBottomRight",      // 贴右下

24,宏定义检测block是否可用

 #define BLOCK_EXEC(block, ...) if (block) { block(__VA_ARGS__); };    // 宏定义之前的用法  if (completionBlock)   {        completionBlock(arg1, arg2);    }     // 宏定义之后的用法  BLOCK_EXEC(completionBlock, arg1, arg2);

 

文/品味_生活(简书)
via:http://www.jianshu.com/p/7c3ee5e67d03
 

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