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  • iOS开发零碎知识点

    记录一些常用和不常用的iOS知识点,防止遗忘丢失。(来源为收集自己项目中用到的或者整理看到博客中的知识点),如有错误,欢迎大家批评指正;如有好的知识点,也欢迎大家联系我,添加上去。谢谢!

    一、调用代码使APP进入后台,达到点击Home键的效果。(私有API)

        [[UIApplication sharedApplication] performSelector:@selector(suspend)];
    

    suspend的英文意思有:暂停; 悬; 挂; 延缓;

    二、带有中文的URL处理。(非UTF-8处理,注意一下)

    大概举个例子,类似下面的URL,里面直接含有中文,可能导致播放不了,那么我们要处理一个这个URL,因为他太操蛋了,居然用中文。

    http://static.tripbe.com/videofiles/视频/我的自拍视频.mp4
    NSString *path  = (__bridge_transfer NSString *)CFURLCreateStringByReplacingPercentEscapesUsingEncoding(NULL,                                                                                                             (__bridge CFStringRef)model.mp4_url,                                                                                                        CFSTR(""),                                                                                                                CFStringConvertNSStringEncodingToEncoding(NSUTF8StringEncoding));
    

    三、获取UIWebView的高度 
    个人最常用的获取方法,感觉这个比较靠谱

    - (void)webViewDidFinishLoad:(UIWebView *)webView  {  
        CGFloat height = [[webView stringByEvaluatingJavaScriptFromString:@"document.body.offsetHeight"] floatValue];  
        CGRect frame = webView.frame;  
        webView.frame = CGRectMake(frame.origin.x, frame.origin.y, frame.size.width, height);  
    }  
    

    四、给UIView设置图片(UILabel一样适用)

    • 第一种方法: 
      利用的UIView的设置背景颜色方法,用图片做图案颜色,然后传给背景颜色。

      UIColor *bgColor = [UIColor colorWithPatternImage: [UIImage imageNamed:@"bgImg.png"];
              UIView *myView = [[UIView alloc] initWithFrame:CGRectMake(0,0,320,480)];
      [myView setBackGroundColor:bgColor];
      
    • 第二种方法:

      UIImage *image = [UIImage imageNamed:@"yourPicName@2x.png"];
      yourView.layer.contents = (__bridge id)image.CGImage;
      //设置显示的图片范围
      yourView.layer.contentsCenter = CGRectMake(0.25,0.25,0.5,0.5);//四个值在0-1之间,对应的为x,y,width,height。
      

    五、去掉UITableView多余的分割线

    yourTableView.tableFooterView = [UIView new];
    

    六、调整cell分割线的位置,两个方法一起用,暴力解决,防脱发

    -(void)viewDidLayoutSubviews {
    
        if ([self.mytableview respondsToSelector:@selector(setSeparatorInset:)]) {
            [self.mytableview setSeparatorInset:UIEdgeInsetsMake(0, 0, 0, 0)];
    
        }
        if ([self.mytableview respondsToSelector:@selector(setLayoutMargins:)])  {
            [self.mytableview setLayoutMargins:UIEdgeInsetsMake(0, 0, 0, 0)];
        }
    
    }
    
    #pragma mark - cell分割线
    - (void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath
    {
        if ([cell respondsToSelector:@selector(setSeparatorInset:)]){
            [cell setSeparatorInset:UIEdgeInsetsMake(0, 0, 0, 0)];
        }
        if ([cell respondsToSelector:@selector(setLayoutMargins:)]) {
            [cell setLayoutMargins:UIEdgeInsetsMake(0, 0, 0, 0)];
        }
    }
    

    七、UILabel和UIImageView的交互userInteractionEabled默认为NO。那么如果你把这两个类做为父试图的话,里面的所有东东都不可以点击哦。曾经有一个人,让我帮忙调试bug,他调试很久没搞定,就是把WMPlayer对象(播放器对象)放到一个UIImageView上面。这样imageView addSubView:wmPlayer 后,播放器的任何东东都不能点击了。userInteractionEabled设置为YES即可。

    八、UISearchController和UISearchBar的Cancle按钮改title问题,简单粗暴

    - (BOOL)searchBarShouldBeginEditing:(UISearchBar *)searchBar
    {
        searchController.searchBar.showsCancelButton = YES;
        UIButton *canceLBtn = [searchController.searchBar valueForKey:@"cancelButton"];
        [canceLBtn setTitle:@"取消" forState:UIControlStateNormal];
        [canceLBtn setTitleColor:[UIColor colorWithRed:14.0/255.0 green:180.0/255.0 blue:0.0/255.0 alpha:1.00] forState:UIControlStateNormal];
        searchBar.showsCancelButton = YES;
        return YES;
    }
    

    九、UITableView收起键盘何必这么麻烦 
    一个属性搞定,效果好(UIScrollView同样可以使用) 
    以前是不是觉得[self.view endEditing:YES];很屌,这个下面的更屌。 
    yourTableView.keyboardDismissMode = UIScrollViewKeyboardDismissModeOnDrag;

    另外一个枚举为UIScrollViewKeyboardDismissModeInteractive,表示在键盘内部滑动,键盘逐渐下去。

    十、NSTimer 
    1、NSTimer计算的时间并不精确 
    2、NSTimer需要添加到runLoop运行才会执行,但是这个runLoop的线程必须是已经开启。 
    3、NSTimer会对它的tagert进行retain,我们必须对其重复性的使用intvailte停止。target如果是self(指UIViewController),那么VC的retainCount+1,如果你不释放NSTimer,那么你的VC就不会dealloc了,内存泄漏了。

    十一、UIViewController没用大小(frame) 
    经常有人在群里问:怎么改变VC的大小啊? 
    瞬间无语。(只有UIView才能设置大小,VC是控制器啊,哥!)

    十二、用十六进制获取UIColor(类方法或者Category都可以,这里我用工具类方法)

    + (UIColor *)colorWithHexString:(NSString *)color
    {
        NSString *cString = [[color stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]] uppercaseString];
    
        // String should be 6 or 8 characters
        if ([cString length] < 6) {
            return [UIColor clearColor];
        }
    
        // strip 0X if it appears
        if ([cString hasPrefix:@"0X"])
            cString = [cString substringFromIndex:2];
        if ([cString hasPrefix:@"#"])
            cString = [cString substringFromIndex:1];
        if ([cString length] != 6)
            return [UIColor clearColor];
    
        // Separate into r, g, b substrings
        NSRange range;
        range.location = 0;
        range.length = 2;
    
        //r
        NSString *rString = [cString substringWithRange:range];
    
        //g
        range.location = 2;
        NSString *gString = [cString substringWithRange:range];
    
        //b
        range.location = 4;
        NSString *bString = [cString substringWithRange:range];
    
        // Scan values
        unsigned int r, g, b;
        [[NSScanner scannerWithString:rString] scanHexInt:&r];
        [[NSScanner scannerWithString:gString] scanHexInt:&g];
        [[NSScanner scannerWithString:bString] scanHexInt:&b];
    
        return [UIColor colorWithRed:((float) r / 255.0f) green:((float) g / 255.0f) blue:((float) b / 255.0f) alpha:1.0f];
    }
    

    十三、获取今天是星期几

    + (NSString *) getweekDayStringWithDate:(NSDate *) date
    {
        NSCalendar * calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar]; // 指定日历的算法
        NSDateComponents *comps = [calendar components:NSWeekdayCalendarUnit fromDate:date];
    
        // 1 是周日,2是周一 3.以此类推
    
        NSNumber * weekNumber = @([comps weekday]);
        NSInteger weekInt = [weekNumber integerValue];
        NSString *weekDayString = @"(周一)";
        switch (weekInt) {
            case 1:
            {
                weekDayString = @"(周日)";
            }
                break;
    
            case 2:
            {
                weekDayString = @"(周一)";
            }
                break;
    
            case 3:
            {
                weekDayString = @"(周二)";
            }
                break;
    
            case 4:
            {
                weekDayString = @"(周三)";
            }
                break;
    
            case 5:
            {
                weekDayString = @"(周四)";
            }
                break;
    
            case 6:
            {
                weekDayString = @"(周五)";
            }
                break;
    
            case 7:
            {
                weekDayString = @"(周六)";
            }
                break;
    
            default:
                break;
        }
        return weekDayString;
    
    }
    

    十四、UIView的部分圆角问题

    UIView *view2 = [[UIView alloc] initWithFrame:CGRectMake(120, 10, 80, 80)];
    view2.backgroundColor = [UIColor redColor];
    [self.view addSubview:view2];
    
    UIBezierPath *maskPath = [UIBezierPath bezierPathWithRoundedRect:view2.bounds byRoundingCorners:UIRectCornerBottomLeft | UIRectCornerBottomRight cornerRadii:CGSizeMake(10, 10)];
    CAShapeLayer *maskLayer = [[CAShapeLayer alloc] init];
    maskLayer.frame = view2.bounds;
    maskLayer.path = maskPath.CGPath;
    view2.layer.mask = maskLayer;
    //其中,
    byRoundingCorners:UIRectCornerBottomLeft | UIRectCornerBottomRight
    //指定了需要成为圆角的角。该参数是UIRectCorner类型的,可选的值有:
    * UIRectCornerTopLeft
    * UIRectCornerTopRight
    * UIRectCornerBottomLeft
    * UIRectCornerBottomRight
    * UIRectCornerAllCorners
    

    从名字很容易看出来代表的意思,使用“|”来组合就好了。

    十五、设置滑动的时候隐藏navigationBar

    navigationController.hidesBarsOnSwipe = Yes;
    

    十六、iOS画虚线 
    记得先 QuartzCore框架的导入

    #import <QuartzCore/QuartzCore.h>
    
    CGContextRef context =UIGraphicsGetCurrentContext();  
    CGContextBeginPath(context);  
    CGContextSetLineWidth(context, 2.0);  
    CGContextSetStrokeColorWithColor(context, [UIColor whiteColor].CGColor);  
    CGFloat lengths[] = {10,10};  
    CGContextSetLineDash(context, 0, lengths,2);  
    CGContextMoveToPoint(context, 10.0, 20.0);  
    CGContextAddLineToPoint(context, 310.0,20.0);  
    CGContextStrokePath(context);  
    CGContextClosePath(context);  
    

    十七、自动布局中多行UILabel,需要设置其preferredMaxLayoutWidth属性才能正常显示多行内容。另外如果出现显示不全文本,可以在计算的结果基础上+0.5。

        CGFloat h = [model.message boundingRectWithSize:CGSizeMake([UIScreen mainScreen].bounds.size.width - kGAP-kAvatar_Size - 2*kGAP, CGFLOAT_MAX) options:NSStringDrawingUsesLineFragmentOrigin attributes:attributes context:nil].size.height+0.5;
    

    十八、 禁止程序运行时自动锁屏 
    [[UIApplication sharedApplication] setIdleTimerDisabled:YES];

    十九、KVC相关,支持操作符 
    KVC同时还提供了很复杂的函数,主要有下面这些 
    ①简单集合运算符 
    简单集合运算符共有@avg, @count , @max , @min ,@sum5种,都表示啥不用我说了吧, 目前还不支持自定义。

    @interface Book : NSObject
    @property (nonatomic,copy)  NSString* name;
    @property (nonatomic,assign)  CGFloat price;
    @end
    @implementation Book
    @end
    
    
    Book *book1 = [Book new];
    book1.name = @"The Great Gastby";
    book1.price = 22;
    Book *book2 = [Book new];
    book2.name = @"Time History";
    book2.price = 12;
    Book *book3 = [Book new];
    book3.name = @"Wrong Hole";
    book3.price = 111;
    
    Book *book4 = [Book new];
    book4.name = @"Wrong Hole";
    book4.price = 111;
    
    NSArray* arrBooks = @[book1,book2,book3,book4];
    NSNumber* sum = [arrBooks valueForKeyPath:@"@sum.price"];
    NSLog(@"sum:%f",sum.floatValue);
    NSNumber* avg = [arrBooks valueForKeyPath:@"@avg.price"];
    NSLog(@"avg:%f",avg.floatValue);
    NSNumber* count = [arrBooks valueForKeyPath:@"@count"];
    NSLog(@"count:%f",count.floatValue);
    NSNumber* min = [arrBooks valueForKeyPath:@"@min.price"];
    NSLog(@"min:%f",min.floatValue);
    NSNumber* max = [arrBooks valueForKeyPath:@"@max.price"];
    NSLog(@"max:%f",max.floatValue);
    
    打印结果
    2016-04-20 16:45:54.696 KVCDemo[1484:127089] sum:256.000000
    2016-04-20 16:45:54.697 KVCDemo[1484:127089] avg:64.000000
    2016-04-20 16:45:54.697 KVCDemo[1484:127089] count:4.000000
    2016-04-20 16:45:54.697 KVCDemo[1484:127089] min:12.000000
    

    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
    %f
    %f
    %f",sum,avg,max,min);
    

    二十、使用MBProgressHud时,尽量不要加到UIWindow上,加self.view上即可。如果加UIWindow上在iPad上,旋转屏幕的时候MBProgressHud不会旋转。之前有人遇到这个bug,我让他改放到self.view上即可解决此bug。

    二十一、强制让App直接退出(非闪退,非崩溃)

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

    二十二、Label行间距

     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;
    

    二十三、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。

    二十四、MRC和ARC混编设置方式 
    在XCode中targets的build phases选项下Compile Sources下选择 不需要arc编译的文件 
    双击输入 -fno-objc-arc 即可 
    MRC工程中也可以使用ARC的类,方法如下: 
    在XCode中targets的build phases选项下Compile Sources下选择要使用arc编译的文件 
    双击输入 -fobjc-arc 即可

    二十五、把tableview里cell的小对勾的颜色改成别的颜色 
    _yourTableView.tintColor = [UIColor redColor];

    二十六、解决同时按两个按钮进两个view的问题 
    [button setExclusiveTouch:YES];

    二十七、修改textFieldplaceholder字体颜色和大小

    textField.placeholder = @"请输入用户名";  
    [textField setValue:[UIColor redColor] forKeyPath:@"_placeholderLabel.textColor"];  
    [textField setValue:[UIFont boldSystemFontOfSize:16] forKeyPath:@"_placeholderLabel.font"];
    

    二十八、禁止textField和textView的复制粘贴菜单

    -(BOOL)canPerformAction:(SEL)action withSender:(id)sender
    {
         if ([UIMenuController sharedMenuController]) {
           [UIMenuController sharedMenuController].menuVisible = NO;
         }
         return NO;
    }
    

    二十九:如何进入我的软件在app store 的页面 
    先用iTunes Link Maker找到软件在访问地址,格式为itms-apps://ax.itunes.apple.com/…,然后

    #define  ITUNESLINK   @"itms-apps://ax.itunes.apple.com/..."
    NSURL *url = [NSURL URLWithString:ITUNESLINK];
    if([[UIApplication sharedApplication] canOpenURL:url]){
         [[UIApplication sharedApplication] openURL:url];
    }
    

    如果把上述地址中itms-apps改为http就可以在浏览器中打开了。可以把这个地址放在自己的网站里,链接到app store。 
    iTunes Link Maker地址:http://itunes.apple.com/linkmaker

    三十、二级三级页面隐藏系统tabbar 
    1、单个处理

    YourViewController *yourVC = [YourViewController new];
    yourVC.hidesBottomBarWhenPushed = YES;
    [self.navigationController pushViewController:yourVC animated:YES];
    

    2.统一在基类里面处理 
    新建一个类BaseNavigationController继承UINavigationController,然后重写 -(void)pushViewController:(UIViewController *)viewController animated:(BOOL)animated这个方法。所有的push事件都走此方法。

    @interface BaseNavigationController : UINavigationController
    
    @end
        -(void)pushViewController:(UIViewController *)viewController animated:(BOOL)animated{
            [super pushViewController:viewController animated:animated];
            if (self.viewControllers.count>1) {
                viewController.hidesBottomBarWhenPushed = YES;
            }
        }
    

    三十一、取消系统的返回手势

       self.navigationController.interactivePopGestureRecognizer.enabled = NO;
    

    三十二、修改UIWebView中字体的大小,颜色

    1、UIWebView设置字体大小,颜色,字体: 
    UIWebView无法通过自身的属性设置字体的一些属性,只能通过html代码进行设置 
    在webView加载完毕后,在

    - (void)webViewDidFinishLoad:(UIWebView *)webView方法中加入js代码  
        NSString *str = @"document.getElementsByTagName('body')[0].style.webkitTextSizeAdjust= '60%'";  
        [_webView stringByEvaluatingJavaScriptFromString:str]; 
    

    或者加入以下代码

    NSString *jsString = [[NSString alloc] initWithFormat:@"document.body.style.fontSize=%f;document.body.style.color=%@",fontSize,fontColor];   
            [webView stringByEvaluatingJavaScriptFromString:jsString];   
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  • 原文地址:https://www.cnblogs.com/r360/p/5763649.html
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