iOS小技巧总结###

参考iOS_小松哥的iOS小技巧总结

总结日常代码生活中的小技巧，随时可用

阿拉伯数字转中文格式
阿拉伯数字转中文格式
UITextField每四位加一个空格,实现代理

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
    // 四位加一个空格
    if ([string isEqualToString:@""])
    {
        // 删除字符
        if ((textField.text.length - 2) % 5 == 0)
        {
            textField.text = [textField.text substringToIndex:textField.text.length - 1];
        }
        return YES;
    }
    else
    {
        if (textField.text.length % 5 == 0)
        {
            textField.text = [NSString stringWithFormat:@"%@ ", textField.text];
        }
    }
    return YES;
}

禁止锁屏

默认情况下，当设备一段时间没有触控动作时，iOS会锁住屏幕。但有一些应用是不需要锁屏的，比如视频播放器。

[UIApplication sharedApplication].idleTimerDisabled = YES;
或
[[UIApplication sharedApplication] setIdleTimerDisabled:YES];

iOS 获取汉字的拼音

+ (NSString *)transform:(NSString *)chinese
{    
    //将NSString装换成NSMutableString 
    NSMutableString *pinyin = [chinese mutableCopy];    
    //将汉字转换为拼音(带音标)    
    CFStringTransform((__bridge CFMutableStringRef)pinyin, NULL, kCFStringTransformMandarinLatin, NO);    
    NSLog(@"%@", pinyin);    
    //去掉拼音的音标    
    CFStringTransform((__bridge CFMutableStringRef)pinyin, NULL, kCFStringTransformStripCombiningMarks, NO);    
    NSLog(@"%@", pinyin);    
    //返回最近结果    
    return pinyin;
 }

手动更改iOS状态栏的颜色

- (void)setStatusBarBackgroundColor:(UIColor *)color
{
    UIView *statusBar = [[[UIApplication sharedApplication] valueForKey:@"statusBarWindow"] valueForKey:@"statusBar"];

    if ([statusBar respondsToSelector:@selector(setBackgroundColor:)])
    {
        statusBar.backgroundColor = color;    
    }
}

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);

修改UITextField中Placeholder的文字颜色

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

关于NSDateFormatter的格式

G: 公元时代，例如AD公元
yy: 年的后2位
yyyy: 完整年
MM: 月，显示为1-12
MMM: 月，显示为英文月份简写,如 Jan
MMMM: 月，显示为英文月份全称，如 Janualy
dd: 日，2位数表示，如02
d: 日，1-2位显示，如 2
EEE: 简写星期几，如Sun
EEEE: 全写星期几，如Sunday
aa: 上下午，AM/PM
H: 时，24小时制，0-23
K：时，12小时制，0-11
m: 分，1-2位
mm: 分，2位
s: 秒，1-2位
ss: 秒，2位
S: 毫秒

UIImage 占用内存大小

UIImage *image = [UIImage imageNamed:@"aa"];
NSUInteger size  = CGImageGetHeight(image.CGImage) * CGImageGetBytesPerRow(image.CGImage);

图片上绘制文字 写一个UIImage的category

- (UIImage *)imageWithTitle:(NSString *)title fontSize:(CGFloat)fontSize
{
    //画布大小
    CGSize size=CGSizeMake(self.size.width,self.size.height);
    //创建一个基于位图的上下文
    UIGraphicsBeginImageContextWithOptions(size,NO,0.0);//opaque:NO  scale:0.0

    [self drawAtPoint:CGPointMake(0.0,0.0)];

    //文字居中显示在画布上
    NSMutableParagraphStyle* paragraphStyle = [[NSParagraphStyle defaultParagraphStyle] mutableCopy];
    paragraphStyle.lineBreakMode = NSLineBreakByCharWrapping;
    paragraphStyle.alignment=NSTextAlignmentCenter;//文字居中

    //计算文字所占的size,文字居中显示在画布上
    CGSize sizeText=[title boundingRectWithSize:self.size options:NSStringDrawingUsesLineFragmentOrigin
                                     attributes:@{NSFontAttributeName:[UIFont systemFontOfSize:fontSize]}context:nil].size;
    CGFloat width = self.size.width;
    CGFloat height = self.size.height;

    CGRect rect = CGRectMake((width-sizeText.width)/2, (height-sizeText.height)/2, sizeText.width, sizeText.height);
    //绘制文字
    [title drawInRect:rect withAttributes:@{ NSFontAttributeName:[UIFont systemFontOfSize:fontSize],NSForegroundColorAttributeName:[ UIColor whiteColor],NSParagraphStyleAttributeName:paragraphStyle}];

    //返回绘制的新图形
    UIImage *newImage= UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return newImage;
}

计算文件大小

//文件大小
- (long long)fileSizeAtPath:(NSString *)path
{
    NSFileManager *fileManager = [NSFileManager defaultManager];

    if ([fileManager fileExistsAtPath:path])
    {
        long long size = [fileManager attributesOfItemAtPath:path error:nil].fileSize;
        return size;
    }

    return 0;
}

//文件夹大小
- (long long)folderSizeAtPath:(NSString *)path
{
    NSFileManager *fileManager = [NSFileManager defaultManager];

    long long folderSize = 0;

    if ([fileManager fileExistsAtPath:path])
    {
        NSArray *childerFiles = [fileManager subpathsAtPath:path];
        for (NSString *fileName in childerFiles)
        {
            NSString *fileAbsolutePath = [path stringByAppendingPathComponent:fileName];
            if ([fileManager fileExistsAtPath:fileAbsolutePath])
            {
                long long size = [fileManager attributesOfItemAtPath:fileAbsolutePath error:nil].fileSize;
                folderSize += size;
            }
        }
    }

    return folderSize;
}

给UIView设置图片

UIImage *image = [UIImage imageNamed:@"image"];
self.MYView.layer.contents = (__bridge id _Nullable)(image.CGImage);
self.MYView.layer.contentsRect = CGRectMake(0, 0, 0.5, 0.5);

防止scrollView手势覆盖侧滑手势

[scrollView.panGestureRecognizerrequireGestureRecognizerToFail:self.navigationController.interactivePopGestureRecognizer];

获取私有属性和成员变量 #import <objc/runtime.h>

//获取私有属性 比如设置UIDatePicker的字体颜色
- (void)setTextColor
{
    //获取所有的属性，去查看有没有对应的属性
    unsigned int count = 0;
    objc_property_t *propertys = class_copyPropertyList([UIDatePicker class], &count);
    for(int i = 0;i < count;i ++)
    {
        //获得每一个属性
        objc_property_t property = propertys[i];
        //获得属性对应的nsstring
        NSString *propertyName = [NSString stringWithCString:property_getName(property) encoding:NSUTF8StringEncoding];
        //输出打印看对应的属性
        NSLog(@"propertyname = %@",propertyName);
        if ([propertyName isEqualToString:@"textColor"])
        {
            [datePicker setValue:[UIColor whiteColor] forKey:propertyName];
        }
    }
}

//获得成员变量 比如修改UIAlertAction的按钮字体颜色
    unsigned int count = 0;
    Ivar *ivars = class_copyIvarList([UIAlertAction class], &count);
    for(int i =0;i < count;i ++)
    {
        Ivar ivar = ivars[i];
        NSString *ivarName = [NSString stringWithCString:ivar_getName(ivar) encoding:NSUTF8StringEncoding];
        NSLog(@"uialertion.ivarName = %@",ivarName);
        if ([ivarName isEqualToString:@"_titleTextColor"])
        {
            [alertOk setValue:[UIColor blueColor] forKey:@"titleTextColor"];
            [alertCancel setValue:[UIColor purpleColor] forKey:@"titleTextColor"];
        }
    }

获取手机安装的应用

Class c =NSClassFromString(@"LSApplicationWorkspace");
id s = [(id)c performSelector:NSSelectorFromString(@"defaultWorkspace")];
NSArray *array = [s performSelector:NSSelectorFromString(@"allInstalledApplications")];
for (id item in array)
{
    NSLog(@"%@",[item performSelector:NSSelectorFromString(@"applicationIdentifier")]);
    //NSLog(@"%@",[item performSelector:NSSelectorFromString(@"bundleIdentifier")]);
    NSLog(@"%@",[item performSelector:NSSelectorFromString(@"bundleVersion")]);
    NSLog(@"%@",[item performSelector:NSSelectorFromString(@"shortVersionString")]);
}

判断两个日期是否在同一周 写在NSDate的category里面

- (BOOL)isSameDateWithDate:(NSDate *)date
{
    //日期间隔大于七天之间返回NO
    if (fabs([self timeIntervalSinceDate:date]) >= 7 * 24 *3600)
    {
        return NO;
    }

    NSCalendar *calender = [NSCalendar currentCalendar];
    calender.firstWeekday = 2;//设置每周第一天从周一开始
    //计算两个日期分别为这年第几周
    NSUInteger countSelf = [calender ordinalityOfUnit:NSCalendarUnitWeekday inUnit:NSCalendarUnitYear forDate:self];
    NSUInteger countDate = [calender ordinalityOfUnit:NSCalendarUnitWeekday inUnit:NSCalendarUnitYear forDate:date];

    //相等就在同一周，不相等就不在同一周
    return countSelf == countDate;
}

应用内打开系统设置界面

//iOS8之后
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:UIApplicationOpenSettingsURLString]];
//如果App没有添加权限，显示的是设定界面。如果App有添加权限（例如通知），显示的是App的设定界面。

获取WebView所有的图片地址

在网页加载完成时，通过js获取图片和添加点击的识别方式

//UIWebView
- (void)webViewDidFinishLoad:(UIWebView *)webView
{
    //这里是js，主要目的实现对url的获取
    static  NSString * const jsGetImages =
    @"function getImages(){\
    var objs = document.getElementsByTagName(\"img\");\
    var imgScr = '';\
    for(var i=0;i<objs.length;i++){\
    imgScr = imgScr + objs[i].src + '+';\
    };\
    return imgScr;\
    };";

    [webView stringByEvaluatingJavaScriptFromString:jsGetImages];//注入js方法
    NSString *urlResult = [webView stringByEvaluatingJavaScriptFromString:@"getImages()"];
    NSArray *urlArray = [NSMutableArray arrayWithArray:[urlResult componentsSeparatedByString:@"+"]];
    //urlResurlt 就是获取到得所有图片的url的拼接；mUrlArray就是所有Url的数组
}

//WKWebView
- (void)webView:(WKWebView *)webView didFinishNavigation:(null_unspecified WKNavigation *)navigation
{
    static  NSString * const jsGetImages =
    @"function getImages(){\
    var objs = document.getElementsByTagName(\"img\");\
    var imgScr = '';\
    for(var i=0;i<objs.length;i++){\
    imgScr = imgScr + objs[i].src + '+';\
    };\
    return imgScr;\
    };";

    [webView evaluateJavaScript:jsGetImages completionHandler:nil];
    [webView evaluateJavaScript:@"getImages()" completionHandler:^(id _Nullable result, NSError * _Nullable error) {
        NSLog(@"%@",result);
    }];
}

获取到webview的高度

CGFloat height = [[self.webView stringByEvaluatingJavaScriptFromString:@"document.body.offsetHeight"] floatValue];

navigationBar变为纯透明

//第一种方法
//导航栏纯透明
[self.navigationBar setBackgroundImage:[UIImage new] forBarMetrics:UIBarMetricsDefault];
//去掉导航栏底部的黑线
self.navigationBar.shadowImage = [UIImage new];

//第二种方法
[[self.navigationBar subviews] objectAtIndex:0].alpha = 0;

navigationBar根据滑动距离的渐变色实现

//第一种
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
    CGFloat offsetToShow = 200.0;//滑动多少就完全显示
    CGFloat alpha = 1 - (offsetToShow - scrollView.contentOffset.y) / offsetToShow;
    [[self.navigationController.navigationBar subviews] objectAtIndex:0].alpha = alpha;
}
//第二种
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
    CGFloat offsetToShow = 200.0;
    CGFloat alpha = 1 - (offsetToShow - scrollView.contentOffset.y) / offsetToShow;

    [self.navigationController.navigationBar setShadowImage:[UIImage new]];
    [self.navigationController.navigationBar setBackgroundImage:[self imageWithColor:[[UIColor orangeColor]colorWithAlphaComponent:alpha]] forBarMetrics:UIBarMetricsDefault];
}

//生成一张纯色的图片
- (UIImage *)imageWithColor:(UIColor *)color
{
    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();

    return theImage;
}

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。

描述文件路径
~/Library/MobileDevice/Provisioning Profiles

navigationItem的BarButtonItem如何紧靠屏幕右边界或者左边界？

一般情况下，右边的item会和屏幕右侧保持一段距离：

image.png

下面是通过添加一个负值宽度的固定间距的item来解决，也可以改变宽度实现不同的间隔：

UIImage *img = [[UIImage imageNamed:@"icon_cog"] imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal];
//宽度为负数的固定间距的系统item
UIBarButtonItem *rightNegativeSpacer = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFixedSpace target:nil action:nil];
[rightNegativeSpacer setWidth:-15];

UIBarButtonItem *rightBtnItem1 = [[UIBarButtonItem alloc]initWithImage:img style:UIBarButtonItemStylePlain target:self action:@selector(rightButtonItemClicked:)];
UIBarButtonItem *rightBtnItem2 = [[UIBarButtonItem alloc]initWithImage:img style:UIBarButtonItemStylePlain target:self action:@selector(rightButtonItemClicked:)];
self.navigationItem.rightBarButtonItems = @[rightNegativeSpacer,rightBtnItem1,rightBtnItem2];

image1.png