iOS 知识-常用小技巧大杂烩
zeng168cn
8年前
<p><img src="https://simg.open-open.com/show/5260173ddd50082fc9d727eb2ac5e48a.jpg" alt="iOS 知识-常用小技巧大杂烩" width="9232" height="3843"></p> <p><br> <strong>1，打印View所有子视图</strong></p> <pre> <code class="language-objectivec">po [[self view]recursiveDescription]</code></pre> <p><strong>2，layoutSubviews调用的调用时机</strong></p> <pre> <code class="language-objectivec">* 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</code></pre> <p><strong>3，NSString过滤特殊字符</strong></p> <pre> <code class="language-objectivec">// 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];</code></pre> <p><strong>4，TransForm属性</strong></p> <pre> <code class="language-objectivec">//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;</code></pre> <p><strong>5，去掉分割线多余15像素</strong></p> <pre> <code class="language-objectivec">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]; } }</code></pre> <p><strong>6，计算方法耗时时间间隔</strong></p> <pre> <code class="language-objectivec">// 获取时间间隔 #define TICK CFAbsoluteTime start = CFAbsoluteTimeGetCurrent(); #define TOCK NSLog(@"Time: %f", CFAbsoluteTimeGetCurrent() - start)</code></pre> <p><strong>7，Color颜色宏定义</strong></p> <pre> <code class="language-objectivec">// 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)]</code></pre> <p><strong>8，Alert提示宏定义</strong></p> <pre> <code class="language-objectivec">#define Alert(_S_, ...) [[[UIAlertView alloc] initWithTitle:@"提示" message:[NSString stringWithFormat:(_S_), ##__VA_ARGS__] delegate:nil cancelButtonTitle:@"确定" otherButtonTitles:nil] show]</code></pre> <p><strong>8，让 iOS 应用直接退出</strong></p> <pre> <code class="language-objectivec">- (void)exitApplication { AppDelegate *app = [UIApplication sharedApplication].delegate; UIWindow *window = app.window; [UIView animateWithDuration:1.0f animations:^{ window.alpha = 0; } completion:^(BOOL finished) { exit(0); }]; }</code></pre> <p><strong>8，NSArray 快速求总和 最大值 最小值 和 平均值 </strong></p> <pre> <code class="language-objectivec">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);</code></pre> <p><strong>9，修改Label中不同文字颜色</strong></p> <pre> <code class="language-objectivec">- (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; }</code></pre> <p><strong>10，播放声音</strong></p> <pre> <code class="language-objectivec"> #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];</code></pre> <p><strong>11，检测是否IPad Pro</strong></p> <pre> <code class="language-objectivec">- (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; }</code></pre> <p><strong>11，修改Tabbar Item的属性</strong></p> <pre> <code class="language-objectivec"> // 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];</code></pre> <p><strong>12，NULL - nil - Nil - NSNULL的区别</strong></p> <pre> <code class="language-objectivec">* 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</code></pre> <p><strong>11，去掉BackBarButtonItem的文字</strong></p> <pre> <code class="language-objectivec">[[UIBarButtonItem appearance] setBackButtonTitlePositionAdjustment:UIOffsetMake(0, -60) forBarMetrics:UIBarMetricsDefault];</code></pre> <p><strong>12，控件不能交互的一些原因</strong></p> <pre> <code class="language-objectivec">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</code></pre> <p><strong>12，修改UITextField中Placeholder的文字颜色</strong></p> <pre> <code class="language-objectivec">[text setValue:[UIColor redColor] forKeyPath:@"_placeholderLabel.textColor"]; }</code></pre> <p><strong>13，视图的生命周期</strong></p> <pre> <code class="language-objectivec">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。</code></pre> <p><strong>14，应用程序的生命周期</strong></p> <pre> <code class="language-objectivec">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</code></pre> <p><strong>15，判断view是不是指定视图的子视图</strong></p> <pre> <code class="language-objectivec"> BOOL isView = [textView isDescendantOfView:self.view];</code></pre> <p><strong>16，判断对象是否遵循了某协议</strong></p> <pre> <code class="language-objectivec">if ([self.selectedController conformsToProtocol:@protocol(RefreshPtotocol)]) { [self.selectedController performSelector:@selector(onTriggerRefresh)]; }</code></pre> <p><strong>17，页面强制横屏</strong></p> <pre> <code class="language-objectivec">#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; }</code></pre> <p><strong>18，系统键盘通知消息</strong></p> <pre> <code class="language-objectivec">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</code></pre> <p><strong>19，关闭navigationController的滑动返回手势</strong></p> <pre> <code class="language-objectivec">self.navigationController.interactivePopGestureRecognizer.enabled = NO;</code></pre> <p><strong>20，设置状态栏为任意的颜色</strong></p> <pre> <code class="language-objectivec">- (void)setStatusColor { UIView *statusBarView = [[UIView alloc] initWithFrame:CGRectMake(0, 0,[UIScreen mainScreen].bounds.size.width, 20)]; statusBarView.backgroundColor = [UIColor orangeColor]; [self.view addSubview:statusBarView]; }</code></pre> <p><strong>21，让Xcode的控制台支持LLDB类型的打印</strong></p> <pre> <code class="language-objectivec">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</code></pre> <p>下次重新运行项目，然后就不报错了。</p> <p><img src="https://simg.open-open.com/show/b72454ef1e9da2e2d389e09a51812731.png" alt="iOS 知识-常用小技巧大杂烩" width="426" height="74"></p> <p><br> <strong>22，Label行间距</strong></p> <pre> <code class="language-objectivec">-（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; }</code></pre> <p><strong>23，UIImageView填充模式</strong></p> <pre> <code class="language-objectivec">@"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</code></pre> <p><strong>24，宏定义检测block是否可用</strong></p> <pre> <code class="language-objectivec">#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);</code></pre> <p> </p> <p>文／品味_生活（简书）<br> via：http://www.jianshu.com/p/7c3ee5e67d03<br> </p>