整理下作为笔记，能够给需要的同学提供帮助则更好。

1.计算总磁盘空间(单位mb)

- (float)diskSize {
    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.计算磁盘可用空间（单位mb）

- (float)diskFreeSize {
    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.计算文件大小（单位byte）

- (float)fileSize {
    NSString *path = [[NSBundle mainBundle] pathForResource:@"sf_muni" ofType:@"pdf"];
    NSFileManager *fileManager = [NSFileManager defaultManager];
    if (![fileManager fileExistsAtPath:path])
        return 0;
    return [[fileManager attributesOfItemAtPath:path error:nil] fileSize];
}

4.获取字符串首字母（字符或汉字都可以）

- (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];
}

5.对数组中的元素按首字母分组排序

- (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];
}

6.获取当前时间

//NSString *format = @"yyyy-MM-dd HH:mm:ss" 或 @"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]];
}

7.十六进制颜色码转为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];
}

8.图片加滤镜

   //filterName
    // 怀旧 --> CIPhotoEffectInstant              单色 --> CIPhotoEffectMono
    // 黑白 --> CIPhotoEffectNoir                 褪色 --> CIPhotoEffectFade
    // 色调 --> CIPhotoEffectTonal                冲印 --> CIPhotoEffectProcess
    // 岁月 --> CIPhotoEffectTransfer             铬黄 --> CIPhotoEffectChrome
- (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;
}

9.图片模糊处理

   //blurName
    // 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;
    }
}

10.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;
}

11.获取IP地址

#import <ifaddrs.h>
#import <arpa/inet.h>

- (NSString *)getIPAddress {
    NSString *address = @"error";
    struct ifaddrs *interfaces = NULL;
    struct ifaddrs *temp_addr = NULL;
    int success = 0;
    success = getifaddrs(&interfaces);
    if (success == 0) {
        temp_addr = interfaces;
        while(temp_addr != NULL) {
            if(temp_addr->ifa_addr->sa_family == AF_INET) {
                if([[NSString stringWithUTF8String:temp_addr->ifa_name] isEqualToString:@"en0"]) {
                    address = [NSString stringWithUTF8String:inet_ntoa(((struct sockaddr_in *)temp_addr->ifa_addr)->sin_addr)];
                }
            }
            temp_addr = temp_addr->ifa_next;
        }
    }
    freeifaddrs(interfaces);
    return address;
}

12.判断字符串中是否有中文

- (BOOL)isHaveChineseInString:(NSString *)string{
    for(NSInteger i = 0; i < [string length]; i++){
        int a = [string characterAtIndex:i];
        if (a > 0x4e00 && a < 0x9fff) {
            return YES;
        }
    }
    return NO;
}

13.判断字符串是否为纯数字

- (BOOL)isAllNum:(NSString *)string{
    unichar c;
    for (int i=0; i<string.length; i++) {
        c=[string characterAtIndex:i];
        if (!isdigit(c)) {
            return NO;
        }
    }
    return YES;
}

14.计算文本高度

- (float)calculateHeightWithContent:(NSString *)content andWidth:(float)width andFontSize:(float)fontSize {
    //初始值，宽度给定值，高度给最大值
    CGSize size = CGSizeMake(width,2000);
    //设置字体大小
    NSDictionary *attributes = @{NSFontAttributeName:[UIFont systemFontOfSize:fontSize]};
    //计算尺寸
    CGRect summaryRect = [content boundingRectWithSize:size options:NSStringDrawingUsesLineFragmentOrigin attributes:attributes        context:nil];
    return summaryRect.size.height;
}

15.获取指定UITableViewCell在屏幕上的实际位置

- (CGRect)cellRectInWindow:(NSIndexPath *)index {
    CGRect rectInTableView = [self.tableView rectForRowAtIndexPath:index];
    return [self.tableView convertRect:rectInTableView toView:[self.tableView superview]];
}