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iOS 常用小技巧总结

iOS 常用小技巧总结

作者: 浩成哥哥 | 来源:发表于2017-12-13 10:32 被阅读0次

    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]

    // 利用这种方法设置颜色和透明值,可不影响子视图背景色

    #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]

    9. 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); 

       }];

    }

    10. 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);

    10. 修改Label中不同文字颜色

    - (void)touchesEnded:(NSSet *)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;

    }

    11. 播放声音

    #import//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];

    12. 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 xss=removed xss=removed xss=removed xss=removed xss=removed xss=removed xss=removed xss=removed xss=removed>> ~/.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。

    25. 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;}

    26. 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

    27. 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);

    28. Debug栏打印时自动把Unicode编码转化成汉字

    // 有时候我们在xcode中打印中文,会打印出Unicode编码,还需要自己去一些在线网站转换,有了插件就方便多了。

    DXXcodeConsoleUnicodePlugin 插件

    29. 设置状态栏文字样式颜色

    [[UIApplication sharedApplication] setStatusBarHidden:NO];

    [[UIApplication sharedApplication] setStatusBarStyle:UIStatusBarStyleLightContent];

    30. 自动生成模型代码的插件

    // 可自动生成模型的代码,省去写模型代码的时间ESJsonFormat-for-Xcode

    31. iOS中的一些手势

    轻击手势(TapGestureRecognizer)

    轻扫手势(SwipeGestureRecognizer)

    长按手势(LongPressGestureRecognizer)

    拖动手势(PanGestureRecognizer)

    捏合手势(PinchGestureRecognizer)

    旋转手势(RotationGestureRecognizer)

    32. iOS 开发中一些相关的路径

    模拟器的位置:

    /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs

    文档安装位置:

    /Applications/Xcode.app/Contents/Developer/Documentation/DocSets

    插件保存路径:

    ~/Library/ApplicationSupport/Developer/Shared/Xcode/Plug-ins

    自定义代码段的保存路径:

    ~/Library/Developer/Xcode/UserData/CodeSnippets/

    如果找不到CodeSnippets文件夹,可以自己新建一个CodeSnippets文件夹。

    证书路径

    ~/Library/MobileDevice/Provisioning Profiles

    33. 获取 iOS 路径的方法

    获取家目录路径的函数

    NSString *homeDir = NSHomeDirectory();

    获取Documents目录路径的方法

    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);

    NSString *docDir = [paths objectAtIndex:0];

    获取Documents目录路径的方法

    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES);

    NSString *cachesDir = [paths objectAtIndex:0];

    获取tmp目录路径的方法:

    NSString *tmpDir = NSTemporaryDirectory();

    34. 字符串相关操作

    去除所有的空格

    [str stringByReplacingOccurrencesOfString:@" " withString:@""]

    去除首尾的空格

    [str stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];

    - (NSString *)uppercaseString;

     全部字符转为大写字母

    - (NSString *)lowercaseString 

    全部字符转为小写字母

    35. 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。

    36. 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

    37. 把tableview里cell的小对勾的颜色改成别的颜色

    _mTableView.tintColor = [UIColor redColor];

    38. 调整tableview的separaLine线的位置

    tableView.separatorInset = UIEdgeInsetsMake(0,100,0,0);

    39. 设置滑动的时候隐藏navigationbar

    navigationController.hidesBarsOnSwipe = Yes

    40. 自动处理键盘事件,实现输入框防遮挡的插件

    IQKeyboardManager

    https://github.com/hackiftekhar/IQKeyboardManager

    41. Quartz2D相关

    图形上下是一个CGContextRef类型的数据。

    图形上下文包含:1,绘图路径(各种各样图形)2,绘图状态(颜色,线宽,样式,旋转,缩放,平移)3,输出目标(绘制到什么地方去?UIView、图片)

    1,获取当前图形上下文

    CGContextRef ctx = UIGraphicsGetCurrentContext();

    2,添加线条

    CGContextMoveToPoint(ctx,20,20);

    3,渲染

    CGContextStrokePath(ctx);CGContextFillPath(ctx);

    4,关闭路径

    CGContextClosePath(ctx);

    5,画矩形

    CGContextAddRect(ctx, CGRectMake(20,20,100,120));

    6,设置线条颜色

    [[UIColor redColor] setStroke];

    7, 设置线条宽度

    CGContextSetLineWidth(ctx,20);

    8,设置头尾样式

    CGContextSetLineCap(ctx, kCGLineCapSquare);

    9,设置转折点样式

    CGContextSetLineJoin(ctx, kCGLineJoinBevel);

    10,画圆

    CGContextAddEllipseInRect(ctx, CGRectMake(30,50,100,100));

    11,指定圆心

    CGContextAddArc(ctx,100,100,50,0, M_PI *2,1);

    12,

    获取图片上下文

    UIGraphicsGetImageFromCurrentImageContext();

    13,保存图形上下文

    CGContextSaveGState(ctx);

    14,恢复图形上下文

    CGContextRestoreGState(ctx)

    42. 屏幕截图

    //1.开启一个与图片相关的图形上下文    UIGraphicsBeginImageContextWithOptions(self.view.bounds.size,NO,0.0);   

     //2.获取当前图形上下文   

     CGContextRef ctx = UIGraphicsGetCurrentContext();  

      //3.获取需要截取的view的layer    

    [self.view.layer renderInContext:ctx];   

     //4.从当前上下文中获取图片   

     UIImage *image = UIGraphicsGetImageFromCurrentImageContext(); 

       //5.关闭图形上下文    

    UIGraphicsEndImageContext();    

    //6.把图片保存到相册    

    UIImageWriteToSavedPhotosAlbum(image, nil, nil, nil);

    43. 隐藏导航栏上的返回字体

    //SwiftUIBarButtonItem.appearance().setBackButtonTitlePositionAdjustment(UIOffsetMake(0, -60), forBarMetrics: .Default)

    //OC[[UIBarButtonItemappearance]setBackButtonTitlePositionAdjustment:UIOffsetMake(0, -60) forBarMetrics:UIBarMetricsDefault];

    44. 解决tableview的分割线短一截

    -(void)viewDidLayoutSubviews{

    if([self.tableView respondsToSelector:@selector(setSeparatorInset:)]){

     [self.tableView setSeparatorInset:UIEdgeInsetsMake(0,0,0,0)];

    }if([self.tableView respondsToSelector:@selector(setLayoutMargins:)]){

    [self.tableView setLayoutMargins:UIEdgeInsetsMake(0,0,0,0)]; 

    }

    }

    -(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]; 

    }}

    45. 动态隐藏NavigationBar

    //1.当我们的手离开屏幕时候隐藏

    - (void)scrollViewWillEndDragging:(UIScrollView *)scrollView withVelocity:(CGPoint)velocity targetContentOffset:(inout CGPoint *)targetContentOffset{

    if(velocity.y >0) {

    [self.navigationController setNavigationBarHidden:YES animated:YES];

    }else{

    [self.navigationController setNavigationBarHidden:NO animated:YES]; 

    }}

    velocity.y这个量,在上滑和下滑时,变化极小(小数),但是因为方向不同,有正负之分,这就很好处理了。

    //2.在滑动过程中隐藏

    //像safari(1) 

    self.navigationController.hidesBarsOnSwipe = YES;

    (2)

    - (void)scrollViewDidScroll:(UIScrollView *)scrollView{

     CGFloat offsetY = scrollView.contentOffset.y + __tableView.contentInset.top;

     CGFloat panTranslationY = [scrollView.panGestureRecognizer translationInView:self.tableView].y;

    if(offsetY >64) {if(panTranslationY >0) { 

    //下滑趋势,显示 

    [self.navigationController setNavigationBarHidden:NO animated:YES];

    }else{

     //上滑趋势,隐藏

     [self.navigationController setNavigationBarHidden:YES animated:YES]; }}

    else{

    [self.navigationController setNavigationBarHidden:NO animated:YES];

     }}

    这里的offsetY >64只是为了在视图滑过navigationBar的高度之后才开始处理,防止影响展示效果。panTranslationY是scrollView的pan手势的手指位置的y值,可能不是太好,因为panTranslationY这个值在较小幅度上下滑动时,可能都为正或都为负,这就使得这一方式不太灵敏.

    效果图

    46. 设置导航栏透明

    //方法一:设置透明度

    [[[self.navigationController.navigationBar subviews]objectAtIndex:0] setAlpha:0.1];

    //方法二:设置背景图片/** * 设置导航栏,使其透明 **/

    - (void)setNavigationBarColor:(UIColor *)color targetController:(UIViewController *)targetViewController{

    //导航条的颜色 以及隐藏导航条的颜色targetViewController.navigationController.navigationBar.shadowImage = [[UIImage alloc]init];

     CGRect rect=CGRectMake(0.0f,0.0f,1.0f,1.0f); 

    UIGraphicsBeginImageContext(rect.size);

    CGContextRef context = UIGraphicsGetCurrentContext(); 

    CGContextSetFillColorWithColor(context, [color CGColor]);

     CGContextFillRect(context, rect);

     UIImage *theImage = UIGraphicsGetImageFromCurrentImageContext();

     UIGraphicsEndImageContext(); 

    [targetViewController.navigationController.navigationBar setBackgroundImage:theImage forBarMetrics:UIBarMetricsDefault];

    }

    47. 设置字体和行间距

    //设置字体和行间距 

    UILabel * lable = [[UILabel alloc]initWithFrame:CGRectMake(50,100,300,200)]; lable.text =@"大家好,我是Frank_chun,在这里我们一起学习新的知识,总结我们遇到的那些坑,共同的学习,共同的进步,共同的努力,只为美好的明天!!!有问题一起相互的探讨--438637472!!!";

    lable.numberOfLines =0;

    lable.font = [UIFont systemFontOfSize:12];

    lable.backgroundColor = [UIColor grayColor];

     [self.view addSubview:lable];

     //设置每个字体之间的间距 

    //NSKernAttributeName 这个对象所对应的值是一个NSNumber对象(包含小数),作用是修改默认字体之间的距离调整,值为0的话表示字距调整是禁用的;

     NSMutableAttributedString * str = [[NSMutableAttributedString alloc]initWithString:lable.text attributes:@{NSKernAttributeName:@(5.0)}];

    //设置某写字体的颜色

    //NSForegroundColorAttributeName 设置字体颜色

    NSRange blueRange = NSMakeRange([[str string] rangeOfString:@"Frank_chun"].location, [[str string] rangeOfString:@"Frank_chun"].length);

    [str addAttribute:NSForegroundColorAttributeName value:[UIColor redColor] range:blueRange];

     NSRange blueRange1 = NSMakeRange([[str string] rangeOfString:@"438637472"].location, [[str string] rangeOfString:@"438637472"].length);

    [str addAttribute:NSForegroundColorAttributeName value:[UIColor redColor] range:blueRange1];

    //设置每行之间的间距 

    //NSParagraphStyleAttributeName 设置段落的样式

    NSMutableParagraphStyle * par = [[NSMutableParagraphStyle alloc]init];

    [par setLineSpacing:20];

    //为某一范围内文字添加某个属性

    //NSMakeRange表示所要的范围,从0到整个文本的长度

    [str addAttribute:NSParagraphStyleAttributeName value:par range:NSMakeRange(0, lable.text.length)];

     [lable setAttributedText:str];

    效果图

    48. 点击button倒计时

    //第一种方法

    //点击button倒计时

    #import "ViewController.h"@interface ViewController ()

    @property (nonatomic, strong) UIButton * timeButton

    ;@property (nonatomic, strong) NSTimer * timer;

    @property (nonatomic, strong)UIButton * btn;

    @end

    @implementation ViewController{

     NSInteger _time;

    }

    - (void)viewDidLoad {

    [super viewDidLoad];

     _time =5;

     self.btn = [UIButton buttonWithType:UIButtonTypeCustom];

     _btn.backgroundColor = [UIColor orangeColor];

    [_btn setTitle:@"获取验证码" forState:UIControlStateNormal];

     _btn.titleLabel.font = [UIFont systemFontOfSize:15];

    [_timeButton setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];

    [_btn addTarget:self action:@selector(btnAction:) forControlEvents:UIControlEventTouchUpInside];

    [self refreshButtonWidth]; 

    [self.view addSubview:self.btn];

    }

    - (void)refreshButtonWidth{ 

    CGFloat width =0;

    if(_btn.enabled){ 

    width =100; 

    }else{

     width =200;

    _btn.center = CGPointMake(self.view.frame.size.width/2,200);

    _btn.bounds = CGRectMake(0,0, width,40); 

    //每次刷新,保证区域正确

    [_btn setBackgroundImage:[self imageWithColor:[UIColor orangeColor] andSize:_btn.frame.size] forState:UIControlStateNormal];

    [_btn setBackgroundImage:[self imageWithColor:[UIColor lightGrayColor] andSize:_btn.frame.size] forState:UIControlStateDisabled];

    }

    - (UIImage *)imageWithColor:(UIColor *)color andSize:(CGSize)aSize{

     CGRect rect = CGRectMake(0.0f,0.0f, aSize.width, aSize.height); 

    UIGraphicsBeginImageContext(rect.size);

     CGContextRef context = UIGraphicsGetCurrentContext(); 

    CGContextSetFillColorWithColor(context, [color CGColor]); 

    CGContextFillRect(context, rect); 

    UIImage *image = UIGraphicsGetImageFromCurrentImageContext(); 

    UIGraphicsEndImageContext();returnimage;

    }

    - (void)btnAction:(UIButton *)sender{

    sender.enabled = NO;

    [self refreshButtonWidth];

    [sender setTitle:[NSString stringWithFormat:@"获取验证码(%zi)", _time] forState:UIControlStateNormal];

    _timer = [NSTimer scheduledTimerWithTimeInterval:0.1target:self selector:@selector(timeDown) userInfo:nil repeats:YES];

    }

    - (void)timeDown{

     _time --;

    if(_time ==0) { 

    [_btn setTitle:@"重新获取" forState:UIControlStateNormal];

     _btn.enabled = YES;

    [self refreshButtonWidth]; 

    [_timer invalidate]; _timer = nil; 

    _time =5;return;

     }

     [_btn setTitle:[NSString stringWithFormat:@"获取验证码(%zi)", _time] forState:UIControlStateNormal];

    }

    //第二种方法#pragma mark -点击发送验证码

    - (void)sendMessage:(UIButton *)btn{

    if(self.phoneField.text.length ==0) {

     [self remindMessage:@"请输入正确的手机号"];

    }else{ 

    __block int timeout=60; 

    //倒计时时间

     dispatch_queue_tqueue=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, ^{

    if(timeout<=0){

     //倒计时结束,关闭

     dispatch_source_cancel(_timer);

     dispatch_async(dispatch_get_main_queue(), ^{

     // 设置界面的按钮显示 根据自己需求设置

     [btn setTitle:@"发送验证码" forState:UIControlStateNormal];

     btn.userInteractionEnabled = YES;

    });

     }else{

     int seconds = timeout %60;

    NSString *strTime = [NSString stringWithFormat:@"%d", seconds];

    if([strTime isEqualToString:@"0"]) {

    strTime = [NSString stringWithFormat:@"%d",60];

    } dispatch_async(dispatch_get_main_queue(), ^{

     //设置界面的按钮显示 根据自己需求设置

     //NSLog(@"____%@",strTime);

    [UIView beginAnimations:nil context:nil];

    [UIView setAnimationDuration:1];

     [btn setTitle:[NSString stringWithFormat:@"%@秒后重新发送",strTime] forState:UIControlStateNormal];

    [UIView commitAnimations]; 

    btn.userInteractionEnabled = NO; 

    }); 

    timeout--; 

    } });

     dispatch_resume(_timer);}

    效果图

    49. UITextField默认占位符是居中显示,让其居上显示

    textField.contentVerticalAlignment = UIControlContentVerticalAlignmentTop;

    50. 解决同时按两个按钮进两个view的问题

    [button setExclusiveTouch:YES];

    51. 图片拉伸

    UIImage* img=[UIImage imageNamed:@"2.png"];

    //原图

    UIEdgeInsets edge=UIEdgeInsetsMake(0,10,0,10);

    //UIImageResizingModeStretch:拉伸模式,通过拉伸UIEdgeInsets指定的矩形区域来填充图片

    //UIImageResizingModeTile:平铺模式,通过重复显示UIEdgeInsets指定的矩形区域来填充图

    img=[imgresizableImageWithCapInsets:edgeresizingMode:UIImageResizingModeStretch];

    self.imageView.image=img;

    52. 修改textFieldplaceholder字体颜色和大小

    textField.placeholder =@"username is in here!";

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

    [textField setValue:[UIFont boldSystemFontOfSize:16] forKeyPath:@"_placeholderLabel.font"];

    53. 修改状态栏字体颜色

    只能设置两种颜色,黑色和白色,系统默认黑色设置为白色方法:

    (1)在plist里面添加Status bar style,值为UIStatusBarStyleLightContent(白色)或UIStatusBarStyleDefault(黑 色)

    (2)在Info.plist中设置UIViewControllerBasedStatusBarAppearance 为NO

    54. 去掉导航栏下边的黑线

    [self.navigationController.navigationBar setBackgroundImage:[[UIImage alloc] init] forBarMetrics:UIBarMetricsDefault];

    self.navigationController.navigationBar.shadowImage = [[UIImage alloc] init];

    55. 修改pagecontrol颜色

    _pageControl.currentPageIndicatorTintColor=SFQRedColor;

    _pageControl.pageIndicatorTintColor=SFQGrayColor;

    56. 去掉UITableView的section的粘性,使其不会悬停

    //有时候使用UITableView所实现的列表,会使用到section,但是又不希望它粘在最顶上而是跟随滚动而消失或者出现

    - (void)scrollViewDidScroll:(UIScrollView *)scrollView {

    if(scrollView == _tableView) {      

        CGFloat sectionHeaderHeight =36;

    if(scrollView.contentOffset.y <= sectionHeaderHeight && scrollView.contentOffset.y >=0) {

     scrollView.contentInset = UIEdgeInsetsMake(-scrollView.contentOffset.y,0,0,0);

      }elseif(scrollView.contentOffset.y >= sectionHeaderHeight) {   

      scrollView.contentInset = UIEdgeInsetsMake(-sectionHeaderHeight,0,0,0);       

       }      }  }

    57. 通过2D仿射函数实现小的动画效果(变大缩小) --可用于自定义pageControl中

    [UIView animateWithDuration:0.3animations:^{  

     imageView.transform = CGAffineTransformMakeScale(2,2);

    } completion:^(BOOL finished) {

    imageView.transform = CGAffineTransformMakeScale(1.0,1.0); 

    }];

    58. UIImage与字符串互转

    //图片转字符串 

     -(NSString *)UIImageToBase64Str:(UIImage *) image  {  

     NSData *data = UIImageJPEGRepresentation(image,1.0f);     

     NSString *encodedImageStr =[data base64EncodedStringWithOptions:NSDataBase64Encoding64CharacterLineLength];

    returnen codedImageStr; 

     }

    //字符串转图片 

     -(UIImage *)Base64StrToUIImage:(NSString *)_encodedImageStr  {

    NSData *_decodedImageData  = [[NSData alloc]initWithBase64Encoding:_encodedImageStr];

     UIImage *_decodedImage= [UIImage imageWithData:_decodedImageData];

    return _decodedImage;  

    }

    59. 判断NSString中是否包含中文

    -(BOOL)isChinese:(NSString *)str{ 

       NSString *match=@"(^[\u4e00-\u9fa5]+$)";

    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"SELF matches %@", match];

    return [predicate evaluateWithObject:str];

    }

    60. NSDate与NSString的相互转化

    -(NSString *)dateToString:(NSDate *)date {  

    // 初始化时间格式控制器 

     NSDateFormatter *matter = [[NSDateFormatter alloc] init];  

    // 设置设计格式 

     [matter setDateFormat:@"yyyy-MM-dd hh:mm:ss zzz"];

    // 进行转换 

     NSString *dateStr = [matter stringFromDate:date];returndateStr;

    }

    -(NSDate *)stringToDate:(NSString *)dateStr { 

     // 初始化时间格式控制器

      NSDateFormatter *matter = [[NSDateFormatter alloc] init];  

    // 设置设计格式 

     [matter setDateFormat:@"yyyy-MM-dd hh:mm:ss zzz"];

    // 进行转换 

     NSDate *date = [matter dateFromString:dateStr];

    return date;

    }

    文章出处:iOS 知识-常用小技巧大杂烩

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