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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

作者: Hurricane_4283 | 来源:发表于2017-11-14 18:31 被阅读10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 = [NSCharacterSetcharacterSetWithCharactersInString:

    @"@/:;()¥「」"、[]{}#%-*+=_\\|~<>$€^•'@#$%^&*()_+'\""];

    // 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

    1#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:^(BOOLfinished) {

    exit(0);

    }];

    }

    10. NSArray 快速求总和 最大值 最小值 和 平均值

    NSArray*array = [NSArrayarrayWithObjects:@"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

    {

    [selfeditStringColor: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

    NSRangerange = [string rangeOfString:editStr];

    NSMutableAttributedString*attribute = [[NSMutableAttributedStringalloc] 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 = [[NSBundlemainBundle]pathForResource:@"pour_milk"ofType:@"wav"];

    //  2.将路劲转化为url

    NSURL*tempUrl = [NSURLfileURLWithPath: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;

    BOOLisIpad =[[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPad;

    BOOLhasIPadProWidth = 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 =

    [[NSMutableAttributedStringalloc] initWithString:self.contentLabel.text];

    NSMutableParagraphStyle*paragraphStyle =  [[NSMutableParagraphStylealloc] 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:[NSCharacterSetwhitespaceCharacterSet]];

    - (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

    [Objective-C]查看源文件复制代码

    ?

    1_mTableView.tintColor = [UIColor redColor];

    38. 调整tableview的separaLine线的位置

    1tableView.separatorInset = UIEdgeInsetsMake(0, 100, 0, 0);

    39. 设置滑动的时候隐藏navigationbar

    1navigationController.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

    //Swift

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

    //OC

    [[UIBarButtonItem appearance] 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:YESanimated:YES];

    }else{

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

    }else{

    //上滑趋势,隐藏

    [self.navigationController setNavigationBarHidden:YESanimated:YES];

    }

    }else{

    [self.navigationController setNavigationBarHidden:NOanimated: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

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

    [str addAttribute:NSForegroundColorAttributeNamevalue:[UIColor redColor] range:blueRange];

    NSRangeblueRange1 =NSMakeRange([[str string] rangeOfString:@"438637472"].location, [[str string] rangeOfString:@"438637472"].length);

    [str addAttribute:NSForegroundColorAttributeNamevalue:[UIColor redColor] range:blueRange1];

    //设置每行之间的间距

    //NSParagraphStyleAttributeName 设置段落的样式

    NSMutableParagraphStyle* par = [[NSMutableParagraphStylealloc]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:NSParagraphStyleAttributeNamevalue: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

    //第一种方法

    //点击button倒计时

    #import "ViewController.h"

    @interfaceViewController ()

    @property(nonatomic, strong) UIButton * timeButton;

    @property(nonatomic, strong)NSTimer* timer;

    @property(nonatomic, strong)UIButton * btn;

    @end@implementationViewController

    {

    NSInteger_time;

    }

    - (void)viewDidLoad {

    [superviewDidLoad];

    _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:selfaction:@selector(btnAction:) forControlEvents:UIControlEventTouchUpInside];

    [selfrefreshButtonWidth];

    [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:[selfimageWithColor:[UIColor orangeColor] andSize:_btn.frame.size] forState:UIControlStateNormal];

    [_btn setBackgroundImage:[selfimageWithColor:[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;

    [selfrefreshButtonWidth];

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

    _timer = [NSTimerscheduledTimerWithTimeInterval:0.1 target:selfselector:@selector(timeDown) userInfo:nilrepeats:YES];

    }

    - (void)timeDown{

    _time --;

    if(_time == 0) {

    [_btn setTitle:@"重新获取"forState:UIControlStateNormal]; _btn.enabled =YES;

    [selfrefreshButtonWidth];

    [_timer invalidate];

    _timer =nil;

    _time = 5 ;

    return;

    }

    [_btn setTitle:[NSStringstringWithFormat:@"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) {

    [selfremindMessage:@"请输入正确的手机号"];

    }else{

    __blockinttimeout=60;

    //倒计时时间

    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, ^{

    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{

    intseconds = timeout % 60;

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

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

    strTime = [NSStringstringWithFormat:@"%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:nilcontext:nil];

    [UIView setAnimationDuration:1];

    [btn setTitle:[NSStringstringWithFormat:@"%@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

    [Objective-C]查看源文件复制代码

    ?

    1textField.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= [img resizableImageWithCapInsets:edge resizingMode:UIImageResizingModeStretch];

    self.imageView.image=img;

    52. 修改textFieldplaceholder字体颜色和大小

    textField.placeholder =@"username is in here!"; [/p][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

    2

    _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:0.3 animations:^{

    imageView.transform = CGAffineTransformMakeScale(2, 2);

    } completion:^(BOOLfinished) {

    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];

    returnencodedImageStr;

    }

    //字符串转图片

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

    {

    NSData*_decodedImageData   = [[NSDataalloc] 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 = [NSPredicatepredicateWithFormat:@"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 = [[NSDateFormatteralloc] 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 = [[NSDateFormatteralloc] 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];

    returndate;

    }

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