iOS 常用的一些公用方法

1. 获取磁盘总空间大小

//磁盘总空间
+ (CGFloat)diskOfAllSizeMBytes{
    CGFloat size = 0.0;
    NSError *error;
    NSDictionary *dic = [[NSFileManager defaultManager] attributesOfFileSystemForPath:NSHomeDirectory() error:&error];
    if (error) {
#ifdef DEBUG
        NSLog(@"error: %@", error.localizedDescription);
#endif
    }else{
        NSNumber *number = [dic objectForKey:NSFileSystemSize];
        size = [number floatValue]/1024/1024;
    }
    return size;
}

2. 获取磁盘可用空间大小

//磁盘可用空间
+ (CGFloat)diskOfFreeSizeMBytes{
    CGFloat size = 0.0;
    NSError *error;
    NSDictionary *dic = [[NSFileManager defaultManager] attributesOfFileSystemForPath:NSHomeDirectory() error:&error];
    if (error) {
#ifdef DEBUG
        NSLog(@"error: %@", error.localizedDescription);
#endif
    }else{
        NSNumber *number = [dic objectForKey:NSFileSystemFreeSize];
        size = [number floatValue]/1024/1024;
    }
    return size;
}

3. 获取指定路径下某个文件的大小

//获取文件大小
+ (long long)fileSizeAtPath:(NSString *)filePath{
    NSFileManager *fileManager = [NSFileManager defaultManager];
    if (![fileManager fileExistsAtPath:filePath]) return 0;
    return [[fileManager attributesOfItemAtPath:filePath error:nil] fileSize];
}

4. 获取文件夹下所有文件的大小

//获取文件夹下所有文件的大小
+ (long long)folderSizeAtPath:(NSString *)folderPath{
    NSFileManager *fileManager = [NSFileManager defaultManager];
    if (![fileManager fileExistsAtPath:folderPath]) return 0;
    NSEnumerator *filesEnumerator = [[fileManager subpathsAtPath:folderPath] objectEnumerator];
    NSString *fileName;
    long long folerSize = 0;
    while ((fileName = [filesEnumerator nextObject]) != nil) {
        NSString *filePath = [folderPath stringByAppendingPathComponent:fileName];
        folerSize += [self fileSizeAtPath:filePath];
    }
    return folerSize;
}

5. 将字符串数组按照元素首字母顺序进行排序分组

//将字符串数组按照元素首字母顺序进行排序分组
+ (NSDictionary *)dictionaryOrderByCharacterWithOriginalArray:(NSArray *)array{
    if (array.count == 0) {
        return nil;
    }
    for (id obj in array) {
        if (![obj isKindOfClass:[NSString class]]) {
            return nil;
        }
    }
    UILocalizedIndexedCollation *indexedCollation = [UILocalizedIndexedCollation currentCollation];
    NSMutableArray *objects = [NSMutableArray arrayWithCapacity:indexedCollation.sectionTitles.count];
    //创建27个分组数组
    for (int i = 0; i < indexedCollation.sectionTitles.count; i++) {
        NSMutableArray *obj = [NSMutableArray array];
        [objects addObject:obj];
    }
    NSMutableArray *keys = [NSMutableArray arrayWithCapacity:objects.count];
    //按字母顺序进行分组
    NSInteger lastIndex = -1;
    for (int i = 0; i < array.count; i++) {
        NSInteger index = [indexedCollation sectionForObject:array[i] collationStringSelector:@selector(uppercaseString)];
        [[objects objectAtIndex:index] addObject:array[i]];
        lastIndex = index;
    }
    //去掉空数组
    for (int i = 0; i < objects.count; i++) {
        NSMutableArray *obj = objects[i];
        if (obj.count == 0) {
            [objects removeObject:obj];
        }
    }
    //获取索引字母
    for (NSMutableArray *obj in objects) {
        NSString *str = obj[0];
        NSString *key = [self firstCharacterWithString:str];
        [keys addObject:key];
    }
    NSMutableDictionary *dic = [NSMutableDictionary dictionary];
    [dic setObject:objects forKey:keys];
    return dic;
}

//获取字符串(或汉字)首字母
+ (NSString *)firstCharacterWithString:(NSString *)string{
    NSMutableString *str = [NSMutableString stringWithString:string];
    CFStringTransform((CFMutableStringRef)str, NULL, kCFStringTransformMandarinLatin, NO);
    CFStringTransform((CFMutableStringRef)str, NULL, kCFStringTransformStripDiacritics, NO);
    NSString *pingyin = [str capitalizedString];
    return [pingyin substringToIndex:1];
}

使用如下:

NSArray *arr = @[@"guangzhou", @"shanghai", @"北京", @"henan", @"hainan"];
NSDictionary *dic = [Utilities dictionaryOrderByCharacterWithOriginalArray:arr];
NSLog(@"\n\ndic: %@", dic);

6. 获取当前时间

//获取当前时间
//format: @"yyyy-MM-dd HH:mm:ss"、@"yyyy年MM月dd日 HH时mm分ss秒"
+ (NSString *)currentDateWithFormat:(NSString *)format{
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    [dateFormatter setDateFormat:format];
    return [dateFormatter stringFromDate:[NSDate date]];
}

7. 计算上次日期距离现在多久, 如 xx 小时前、xx 分钟前等

/**
 *  计算上次日期距离现在多久
 *
 *  @param lastTime    上次日期(需要和格式对应)
 *  @param format1     上次日期格式
 *  @param currentTime 最近日期(需要和格式对应)
 *  @param format2     最近日期格式
 *
 *  @return xx分钟前、xx小时前、xx天前
 */
+ (NSString *)timeIntervalFromLastTime:(NSString *)lastTime
                        lastTimeFormat:(NSString *)format1
                         ToCurrentTime:(NSString *)currentTime
                     currentTimeFormat:(NSString *)format2{
    //上次时间
    NSDateFormatter *dateFormatter1 = [[NSDateFormatter alloc]init];
    dateFormatter1.dateFormat = format1;
    NSDate *lastDate = [dateFormatter1 dateFromString:lastTime];
    //当前时间
    NSDateFormatter *dateFormatter2 = [[NSDateFormatter alloc]init];
    dateFormatter2.dateFormat = format2;
    NSDate *currentDate = [dateFormatter2 dateFromString:currentTime];
    return [Utilities timeIntervalFromLastTime:lastDate ToCurrentTime:currentDate];
}

+ (NSString *)timeIntervalFromLastTime:(NSDate *)lastTime ToCurrentTime:(NSDate *)currentTime{
    NSTimeZone *timeZone = [NSTimeZone systemTimeZone];
    //上次时间
    NSDate *lastDate = [lastTime dateByAddingTimeInterval:[timeZone secondsFromGMTForDate:lastTime]];
    //当前时间
    NSDate *currentDate = [currentTime dateByAddingTimeInterval:[timeZone secondsFromGMTForDate:currentTime]];
    //时间间隔
    NSInteger intevalTime = [currentDate timeIntervalSinceReferenceDate] - [lastDate timeIntervalSinceReferenceDate];

    //秒、分、小时、天、月、年
    NSInteger minutes = intevalTime / 60;
    NSInteger hours = intevalTime / 60 / 60;
    NSInteger day = intevalTime / 60 / 60 / 24;
    NSInteger month = intevalTime / 60 / 60 / 24 / 30;
    NSInteger yers = intevalTime / 60 / 60 / 24 / 365;

    if (minutes <= 10) {
        return  @"刚刚";
    }else if (minutes < 60){
        return [NSString stringWithFormat: @"%ld分钟前",(long)minutes];
    }else if (hours < 24){
        return [NSString stringWithFormat: @"%ld小时前",(long)hours];
    }else if (day < 30){
        return [NSString stringWithFormat: @"%ld天前",(long)day];
    }else if (month < 12){
        NSDateFormatter * df =[[NSDateFormatter alloc]init];
        df.dateFormat = @"M月d日";
        NSString * time = [df stringFromDate:lastDate];
        return time;
    }else if (yers >= 1){
        NSDateFormatter * df =[[NSDateFormatter alloc]init];
        df.dateFormat = @"yyyy年M月d日";
        NSString * time = [df stringFromDate:lastDate];
        return time;
    }
    return @"";
}

使用如下:

NSLog(@"\n\nresult: %@", [Utilities timeIntervalFromLastTime:@"2015年12月8日 15:50"
                                           lastTimeFormat:@"yyyy年MM月dd日 HH:mm"
                                            ToCurrentTime:@"2015/12/08 16:12"
                                        currentTimeFormat:@"yyyy/MM/dd HH:mm"]);

7. 获取当前时间

//获取当前时间
//format: @"yyyy-MM-dd HH:mm:ss"、@"yyyy年MM月dd日 HH时mm分ss秒"
+ (NSString *)currentDateWithFormat:(NSString *)format{
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    [dateFormatter setDateFormat:format];
    return [dateFormatter stringFromDate:[NSDate date]];
}

8. 计算上次日期距离现在多久, 如 xx 小时前、xx 分钟前等

/**
 *  计算上次日期距离现在多久
 *
 *  @param lastTime    上次日期(需要和格式对应)
 *  @param format1     上次日期格式
 *  @param currentTime 最近日期(需要和格式对应)
 *  @param format2     最近日期格式
 *
 *  @return xx分钟前、xx小时前、xx天前
 */
+ (NSString *)timeIntervalFromLastTime:(NSString *)lastTime
                        lastTimeFormat:(NSString *)format1
                         ToCurrentTime:(NSString *)currentTime
                     currentTimeFormat:(NSString *)format2{
    //上次时间
    NSDateFormatter *dateFormatter1 = [[NSDateFormatter alloc]init];
    dateFormatter1.dateFormat = format1;
    NSDate *lastDate = [dateFormatter1 dateFromString:lastTime];
    //当前时间
    NSDateFormatter *dateFormatter2 = [[NSDateFormatter alloc]init];
    dateFormatter2.dateFormat = format2;
    NSDate *currentDate = [dateFormatter2 dateFromString:currentTime];
    return [Utilities timeIntervalFromLastTime:lastDate ToCurrentTime:currentDate];
}

+ (NSString *)timeIntervalFromLastTime:(NSDate *)lastTime ToCurrentTime:(NSDate *)currentTime{
    NSTimeZone *timeZone = [NSTimeZone systemTimeZone];
    //上次时间
    NSDate *lastDate = [lastTime dateByAddingTimeInterval:[timeZone secondsFromGMTForDate:lastTime]];
    //当前时间
    NSDate *currentDate = [currentTime dateByAddingTimeInterval:[timeZone secondsFromGMTForDate:currentTime]];
    //时间间隔
    NSInteger intevalTime = [currentDate timeIntervalSinceReferenceDate] - [lastDate timeIntervalSinceReferenceDate];

    //秒、分、小时、天、月、年
    NSInteger minutes = intevalTime / 60;
    NSInteger hours = intevalTime / 60 / 60;
    NSInteger day = intevalTime / 60 / 60 / 24;
    NSInteger month = intevalTime / 60 / 60 / 24 / 30;
    NSInteger yers = intevalTime / 60 / 60 / 24 / 365;

    if (minutes <= 10) {
        return  @"刚刚";
    }else if (minutes < 60){
        return [NSString stringWithFormat: @"%ld分钟前",(long)minutes];
    }else if (hours < 24){
        return [NSString stringWithFormat: @"%ld小时前",(long)hours];
    }else if (day < 30){
        return [NSString stringWithFormat: @"%ld天前",(long)day];
    }else if (month < 12){
        NSDateFormatter * df =[[NSDateFormatter alloc]init];
        df.dateFormat = @"M月d日";
        NSString * time = [df stringFromDate:lastDate];
        return time;
    }else if (yers >= 1){
        NSDateFormatter * df =[[NSDateFormatter alloc]init];
        df.dateFormat = @"yyyy年M月d日";
        NSString * time = [df stringFromDate:lastDate];
        return time;
    }
    return @"";
}

使用如下:

NSLog(@"\n\nresult: %@", [Utilities timeIntervalFromLastTime:@"2015年12月8日 15:50"
                                           lastTimeFormat:@"yyyy年MM月dd日 HH:mm"
                                            ToCurrentTime:@"2015/12/08 16:12"
                                        currentTimeFormat:@"yyyy/MM/dd HH:mm"]);

9. 判断手机号码格式是否正确

//判断手机号码格式是否正确
+ (BOOL)valiMobile:(NSString *)mobile{
    mobile = [mobile stringByReplacingOccurrencesOfString:@" " withString:@""];
    if (mobile.length != 11)
    {
        return NO;
    }else{
        /**
         * 移动号段正则表达式
         */
        NSString *CM_NUM = @"^((13[4-9])|(147)|(15[0-2,7-9])|(178)|(18[2-4,7-8]))\\d{8}|(1705)\\d{7}$";
        /**
         * 联通号段正则表达式
         */
        NSString *CU_NUM = @"^((13[0-2])|(145)|(15[5-6])|(176)|(18[5,6]))\\d{8}|(1709)\\d{7}$";
        /**
         * 电信号段正则表达式
         */
        NSString *CT_NUM = @"^((133)|(153)|(177)|(18[0,1,9]))\\d{8}$";
        NSPredicate *pred1 = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", CM_NUM];
        BOOL isMatch1 = [pred1 evaluateWithObject:mobile];
        NSPredicate *pred2 = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", CU_NUM];
        BOOL isMatch2 = [pred2 evaluateWithObject:mobile];
        NSPredicate *pred3 = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", CT_NUM];
        BOOL isMatch3 = [pred3 evaluateWithObject:mobile];

        if (isMatch1 || isMatch2 || isMatch3) {
            return YES;
        }else{
            return NO;
        }
    }
}

10. 判断邮箱格式是否正确

//利用正则表达式验证
+ (BOOL)isAvailableEmail:(NSString *)email {
    NSString *emailRegex = @"[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,4}";
    NSPredicate *emailTest = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", emailRegex];
    return [emailTest evaluateWithObject:email];
}

11. 将十六进制颜色转换为 UIColor 对象

//将十六进制颜色转换为 UIColor 对象
+ (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" or "#" 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];
}

12. 对图片进行滤镜处理

#pragma mark - 对图片进行滤镜处理
// 怀旧 --> CIPhotoEffectInstant                         单色 --> CIPhotoEffectMono
// 黑白 --> CIPhotoEffectNoir                            褪色 --> CIPhotoEffectFade
// 色调 --> CIPhotoEffectTonal                           冲印 --> CIPhotoEffectProcess
// 岁月 --> CIPhotoEffectTransfer                        铬黄 --> CIPhotoEffectChrome
// CILinearToSRGBToneCurve, CISRGBToneCurveToLinear, CIGaussianBlur, CIBoxBlur, CIDiscBlur, CISepiaTone, CIDepthOfField
+ (UIImage *)filterWithOriginalImage:(UIImage *)image filterName:(NSString *)name{
    CIContext *context = [CIContext contextWithOptions:nil];
    CIImage *inputImage = [[CIImage alloc] initWithImage:image];
    CIFilter *filter = [CIFilter filterWithName:name];
    [filter setValue:inputImage forKey:kCIInputImageKey];
    CIImage *result = [filter valueForKey:kCIOutputImageKey];
    CGImageRef cgImage = [context createCGImage:result fromRect:[result extent]];
    UIImage *resultImage = [UIImage imageWithCGImage:cgImage];
    CGImageRelease(cgImage);
    return resultImage;
}

13. 对图片进行模糊处理

#pragma mark - 对图片进行模糊处理
// CIGaussianBlur ---> 高斯模糊
// CIBoxBlur      ---> 均值模糊(Available in iOS 9.0 and later)
// CIDiscBlur     ---> 环形卷积模糊(Available in iOS 9.0 and later)
// CIMedianFilter ---> 中值模糊, 用于消除图像噪点, 无需设置radius(Available in iOS 9.0 and later)
// CIMotionBlur   ---> 运动模糊, 用于模拟相机移动拍摄时的扫尾效果(Available in iOS 9.0 and later)
+ (UIImage *)blurWithOriginalImage:(UIImage *)image blurName:(NSString *)name radius:(NSInteger)radius{
    CIContext *context = [CIContext contextWithOptions:nil];
    CIImage *inputImage = [[CIImage alloc] initWithImage:image];
    CIFilter *filter;
    if (name.length != 0) {
        filter = [CIFilter filterWithName:name];
        [filter setValue:inputImage forKey:kCIInputImageKey];
        if (![name isEqualToString:@"CIMedianFilter"]) {
            [filter setValue:@(radius) forKey:@"inputRadius"];
        }
        CIImage *result = [filter valueForKey:kCIOutputImageKey];
        CGImageRef cgImage = [context createCGImage:result fromRect:[result extent]];
        UIImage *resultImage = [UIImage imageWithCGImage:cgImage];
        CGImageRelease(cgImage);
        return resultImage;
    }else{
        return nil;
    }
}

14. 调整图片饱和度、亮度、对比度

/**
 *  调整图片饱和度, 亮度, 对比度
 *
 *  @param image      目标图片
 *  @param saturation 饱和度
 *  @param brightness 亮度: -1.0 ~ 1.0
 *  @param contrast   对比度
 *
 */
+ (UIImage *)colorControlsWithOriginalImage:(UIImage *)image
                                 saturation:(CGFloat)saturation
                                 brightness:(CGFloat)brightness
                                   contrast:(CGFloat)contrast{
    CIContext *context = [CIContext contextWithOptions:nil];
    CIImage *inputImage = [[CIImage alloc] initWithImage:image];
    CIFilter *filter = [CIFilter filterWithName:@"CIColorControls"];
    [filter setValue:inputImage forKey:kCIInputImageKey];

    [filter setValue:@(saturation) forKey:@"inputSaturation"];
    [filter setValue:@(brightness) forKey:@"inputBrightness"];
    [filter setValue:@(contrast) forKey:@"inputContrast"];

    CIImage *result = [filter valueForKey:kCIOutputImageKey];
    CGImageRef cgImage = [context createCGImage:result fromRect:[result extent]];
    UIImage *resultImage = [UIImage imageWithCGImage:cgImage];
    CGImageRelease(cgImage);
    return resultImage;
}

15. 创建一张实时模糊效果 View (毛玻璃效果)

//Avilable in iOS 8.0 and later
+ (UIVisualEffectView *)effectViewWithFrame:(CGRect)frame{
    UIBlurEffect *effect = [UIBlurEffect effectWithStyle:UIBlurEffectStyleLight];
    UIVisualEffectView *effectView = [[UIVisualEffectView alloc] initWithEffect:effect];
    effectView.frame = frame;
    return effectView;
}

全屏截图

//全屏截图
+ (UIImage *)shotScreen{
    UIWindow *window = [UIApplication sharedApplication].keyWindow;
    UIGraphicsBeginImageContext(window.bounds.size);
    [window.layer renderInContext:UIGraphicsGetCurrentContext()];
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return image;
}

17. 截取一张 view 生成图片

//截取view生成一张图片
+ (UIImage *)shotWithView:(UIView *)view{
    UIGraphicsBeginImageContext(view.bounds.size);
    [view.layer renderInContext:UIGraphicsGetCurrentContext()];
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return image;
}

18. 截取view中某个区域生成一张图片

//截取view中某个区域生成一张图片
+ (UIImage *)shotWithView:(UIView *)view scope:(CGRect)scope{
    CGImageRef imageRef = CGImageCreateWithImageInRect([self shotWithView:view].CGImage, scope);
    UIGraphicsBeginImageContext(scope.size);
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGRect rect = CGRectMake(0, 0, scope.size.width, scope.size.height);
    CGContextTranslateCTM(context, 0, rect.size.height);//下移
    CGContextScaleCTM(context, 1.0f, -1.0f);//上翻
    CGContextDrawImage(context, rect, imageRef);
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    CGImageRelease(imageRef);
    CGContextRelease(context);
    return image;

19. 压缩图片到指定尺寸大小

//压缩图片到指定尺寸大小
+ (UIImage *)compressOriginalImage:(UIImage *)image toSize:(CGSize)size{
    UIImage *resultImage = image;
    UIGraphicsBeginImageContext(size);
    [resultImage drawInRect:CGRectMake(0, 0, size.width, size.height)];
    UIGraphicsEndImageContext();
    return resultImage;
}

20. 压缩图片到指定文件大小

//压缩图片到指定文件大小
+ (NSData *)compressOriginalImage:(UIImage *)image toMaxDataSizeKBytes:(CGFloat)size{
    NSData *data = UIImageJPEGRepresentation(image, 1.0);
    CGFloat dataKBytes = data.length/1000.0;
    CGFloat maxQuality = 0.9f;
    CGFloat lastData = dataKBytes;
    while (dataKBytes > size && maxQuality > 0.01f) {
        maxQuality = maxQuality - 0.01f;
        data = UIImageJPEGRepresentation(image, maxQuality);
        dataKBytes = data.length/1000.0;
        if (lastData == dataKBytes) {
            break;
        }else{
            lastData = dataKBytes;
        }
    }
    return data;
}

26. 绘制虚线

/*
  ** lineFrame:     虚线的 frame
  ** length:        虚线中短线的宽度
  ** spacing:       虚线中短线之间的间距
  ** color:         虚线中短线的颜色
*/
+ (UIView *)createDashedLineWithFrame:(CGRect)lineFrame
                           lineLength:(int)length
                          lineSpacing:(int)spacing
                            lineColor:(UIColor *)color{
    UIView *dashedLine = [[UIView alloc] initWithFrame:lineFrame];
    dashedLine.backgroundColor = [UIColor clearColor];
    CAShapeLayer *shapeLayer = [CAShapeLayer layer];
    [shapeLayer setBounds:dashedLine.bounds];
    [shapeLayer setPosition:CGPointMake(CGRectGetWidth(dashedLine.frame) / 2, CGRectGetHeight(dashedLine.frame))];
    [shapeLayer setFillColor:[UIColor clearColor].CGColor];
    [shapeLayer setStrokeColor:color.CGColor];
    [shapeLayer setLineWidth:CGRectGetHeight(dashedLine.frame)];
    [shapeLayer setLineJoin:kCALineJoinRound];
    [shapeLayer setLineDashPattern:[NSArray arrayWithObjects:[NSNumber numberWithInt:length], [NSNumber numberWithInt:spacing], nil]];
    CGMutablePathRef path = CGPathCreateMutable();
    CGPathMoveToPoint(path, NULL, 0, 0);
    CGPathAddLineToPoint(path, NULL, CGRectGetWidth(dashedLine.frame), 0);
    [shapeLayer setPath:path];
    CGPathRelease(path);
    [dashedLine.layer addSublayer:shapeLayer];
    return dashedLine;
}

27. 将字典对象转换为 JSON 字符串

+ (NSString *)jsonPrettyStringEncoded:(NSDictionary *)dictionary{
    if ([NSJSONSerialization isValidJSONObject:dictionary ]) {
        NSError *error;
        NSData *jsonData = [NSJSONSerialization dataWithJSONObject:dictionary options:NSJSONWritingPrettyPrinted error:&error];
        if (!error) {
            NSString *json = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];
            return json;
        }
    }
    return nil;
}

28.将数组对象转换为 JSON 字符串

+ (NSString *)jsonPrettyStringEncoded:(NSArray *)array{
    if ([NSJSONSerialization isValidJSONObject:array]) {
        NSError *error;
        NSData *jsonData = [NSJSONSerialization dataWithJSONObject:array options:NSJSONWritingPrettyPrinted error:&error];
        if (!error) {
            NSString *json = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];
            return json;
        }
    }
    return nil;
}