设置多少时间前

// 几天前 几分钟前..
+ (NSString *)updateTimeForTimeInterval:(NSInteger)timeInterval {
    
    // 获取当前时时间戳 1466386762.345715 十位整数 6位小数
    NSTimeInterval currentTime = [[NSDate date] timeIntervalSince1970];
    // 创建歌曲时间戳(后台返回的时间 一般是13位数字)
    NSTimeInterval createTime = timeInterval;
    // 时间差
    NSTimeInterval time = currentTime - createTime;
    if (time < 60) {
        return @"刚刚";
    }
    NSInteger minutes = time / 60;
    if (minutes < 60) {
        
        return [NSString stringWithFormat:@"%ld分钟前", minutes];
    }
    // 秒转小时
    NSInteger hours = time / 3600;
    if (hours < 24) {
        return [NSString stringWithFormat:@"%ld小时前",hours];
    }
    // 秒转天数
    NSInteger days = time / 3600 / 24;
    if (days < 30) {
        return [NSString stringWithFormat:@"%ld天前",days];
    }
    // 秒转月
    NSInteger months = time / 3600 / 24 / 30;
    if (months < 12) {
        return [NSString stringWithFormat:@"%ld月前",months];
    }
    // 秒转年
    NSInteger years = time / 3600 / 24 / 30 / 12;
    return [NSString stringWithFormat:@"%ld年前",years];
}

设置多样文本 - 关键字、字体大小、高亮字体、字体颜色以及行间距

+ (NSAttributedString *)attStringWithString:(NSString *)string
                                    keyWord:(NSString *)keyWord
                                       font:(UIFont *)font
                           highlightedColor:(UIColor *)highlightedcolor
                                  textColor:(UIColor *)textColor
                                  lineSpace:(CGFloat)lineSpace {
    if (string.length) {
        
        NSMutableAttributedString *attStr = [[NSMutableAttributedString alloc] initWithString:string];
        if (!keyWord || keyWord.length == 0) {
            NSRange allRange = NSMakeRange(0, string.length);
            [attStr addAttribute:NSFontAttributeName value:font range:allRange];
            [attStr addAttribute:NSForegroundColorAttributeName value:textColor range:allRange];
            
            NSMutableParagraphStyle *style = [[NSMutableParagraphStyle alloc] init];
            style.lineSpacing = lineSpace;
            [attStr addAttribute:NSParagraphStyleAttributeName value:style range:allRange];
            return attStr;
        }
        NSRange range = [string rangeOfString:keyWord options:NSCaseInsensitiveSearch];
        // 找到了关键字
        if (range.location != NSNotFound) {
            NSRange allRange = NSMakeRange(0, string.length);
            [attStr addAttribute:NSFontAttributeName value:font range:allRange];
            [attStr addAttribute:NSForegroundColorAttributeName value:textColor range:allRange];
            [attStr addAttribute:NSForegroundColorAttributeName value:highlightedcolor range:range];
            
            NSMutableParagraphStyle *style = [[NSMutableParagraphStyle alloc] init];
            style.lineSpacing = lineSpace;
            [attStr addAttribute:NSParagraphStyleAttributeName value:style range:allRange];
        } else {
            NSRange allRange = NSMakeRange(0, string.length);
            [attStr addAttribute:NSFontAttributeName value:font range:allRange];
            [attStr addAttribute:NSForegroundColorAttributeName value:textColor range:allRange];
            
            NSMutableParagraphStyle *style = [[NSMutableParagraphStyle alloc] init];
            style.lineSpacing = lineSpace; 
            [attStr addAttribute:NSParagraphStyleAttributeName value:style range:allRange];
            return attStr;
        }
        return attStr.copy;
    }
    return [[NSAttributedString alloc] init];
}

判断是否为空字符串

/**
 *  判断字符串是否为空
 */
+ (BOOL)isBlankString:(NSString *)string {
    
    if (string == nil || string == NULL) {
        return YES;
    }
    if ([string isKindOfClass:[NSNull class]]) {
        return YES;
    }
    if ([string isKindOfClass:[NSDictionary class]]) {
        return YES;
    }
    if ([string isKindOfClass:[NSString class]] == NO) {
        return YES;
    }
    if ([[string stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]] length] == 0) {
        return YES;
    }
    if ([string isEqualToString:@""]) {
        return YES;
    }
    return NO;
}

把颜色转换成图片

+(UIImage *)imageWithColor:(UIColor *)color
{
    //1.设定图片大小
    CGRect rect = CGRectMake(0.0f, 0.0f, 1.0f, 1.0f);
    //2.开始图片上下文
    UIGraphicsBeginImageContext(rect.size);
    //3.拿到当前上下文
    CGContextRef context = UIGraphicsGetCurrentContext();
    //4.设置上下文颜色
    CGContextSetFillColorWithColor(context,color.CGColor);
    //5.填充上下文
    CGContextFillRect(context, rect);
    //6.从当前图片上下文获取图片
    UIImage * image = UIGraphicsGetImageFromCurrentImageContext();
    //7.图片上下文
    UIGraphicsEndImageContext();
    return image;
}

以上几点是我在别人的项目中新学到的知识点，以后会分享更多！