NSString

字符串互转（数组，字典）

时间戳转为指定字符串

/**
 *  @method 时间戳装换为指定格式
 *
 *  @param time  时间戳
 *  @param formatter 转换格式
 *  @result NSString 字符串
 */
+ (NSString *)timestampChange:(NSInteger)time Formatter:(NSString *)formatter
{
    NSString *strTime;
    
    NSDate *newdate=[NSDate dateWithTimeIntervalSince1970:time/1000];//服务器传回来要除1000
    
    NSDateFormatter *dateformatter=[NSDateFormatter new];//定义时间格式
    
    [dateformatter setDateFormat:formatter];
    
    strTime =[dateformatter stringFromDate:newdate];//转为字符串
    
    return strTime;
}

字符串处理

 NSString *filename=@"ios.doc";

#-----获取指定字符，根据小数点获取，获取小数点前面的数字
NSRange range = [str rangeOfString:@"."];
NSString *b = [str substringWithRange:NSMakeRange(0,range.location - 1)];



#-----判断一个字符串是否是 ios 开头
 bool m = [filename hasPrefix:@"ios"]; 
#-----判断一个字符串是否是 .doc 结尾
 bool n = [filename hasSuffix:@".doc"];
#-----将字符串根据某个字符分离成数组
NSString *filename = @"a,b,bb,dd,";
NSArray *newArray3 = [filename componentsSeparatedByString:@","];
#-----将字符串数组用 逗号分离开
NSArray *dataArray = @[@"111",@"222",@"333",@"444",@"555"];
NSString *str = [dataArray componentsJoinedByString:@","];
NSLog(@"%@",str);
#-----替换所有含有字符 i 的字符(也可以删除-龙换成空字符串)
if([filename containsString:@"i"])
{
    filename = [filename stringByReplacingOccurrencesOfString:@"i" withString:@"龙"];
}    
#-----判断一个字符串中是否存在某个字符
if([filename containsString:@","])
{
}

if([filename rangeOfString:@"."].location == NSNotFound )
{
    NSLog(@"不存在");
}
else
{
    NSLog(@"存在");
}

字符串转整型

NSString *num_2=@"3443";
int num=[num_2 intValue];
NSLog(@"%d",num);

删除字符串最后一位

- (NSString *)clearLastString:(NSString *)str
{
    if(str.length > 0)
    {
        str =  [str substringWithRange:NSMakeRange(0, [str length] - 1)];
    }
    return str;
}

判断是否为空

- (BOOL) isNullString:(id)string
{
    if(string == nil)
   {
       return YES;
   }
   else if([string isKindOfClass:[NSNull class]])
   {
        return YES;
   }
   else if([string isEqualToString:@"(null)"])
   {
       return YES;
   }
   else if([string isEqualToString:@""])
   {
       return YES;
   }
   else if([[string stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]] length] == 0)
   {
       return YES;
   }
   else
   {
     return NO;
   }
}

UTF-8 编码

解码
url = [url stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
编码
url = [url stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];

计算文字高度

/**
 *  @method 获取指定宽度width的字符串的高度
 *
 *  @param text 文本
 *  @param Width 限制字符串显示区域的宽度
 *  @param font  Lab的Font
 *  @result CGFloat 返回的高度
 */
- (CGFloat)HeightWithText:(NSString *)text constrainedToWidth:(CGFloat)width LabFont:(UIFont *)font
{
    CGSize textSize=[text boundingRectWithSize:CGSizeMake(width, MAXFLOAT)  options:NSStringDrawingUsesLineFragmentOrigin attributes:@{NSFontAttributeName:font} context:nil].size;
    CGFloat height = textSize.height + 5;
    
    return height;
    
}

计算文字宽度

/**
 *  @method 获取指定宽度width的字符串的宽度
 *
 *  @param text 文本
 *  @param Width 限制字符串显示区域的宽度
 *  @param font  Lab的Font
 *  @result CGFloat 返回的宽度
 */
- (CGFloat)widthWithText:(NSString *)text constrainedToHeight:(CGFloat)height LabFont:(UIFont *)font
{
    CGSize textSize =[text boundingRectWithSize:CGSizeMake(MAXFLOAT,height)  options:NSStringDrawingUsesLineFragmentOrigin attributes:@{NSFontAttributeName:font} context:nil].size;
    CGFloat width = textSize.width + 5;
    
    return width;
    
}

坑
注意：返回的 height,width 要 +5 不然会显示不出来

计算富文本高度（带间距）

/**
 *  @method 获取指定宽度width的带间距富文本的高度
 *
 *  @param text 富文本
 *  @param Width 限制字符串显示区域的宽度
 *  @param font  富文本的Font
 *  @param style  富文本的style
 *  @result CGFloat 返回的高度
 */
- (CGFloat)HeightWithAttributedString:(NSMutableAttributedString *)text andFont:(UIFont *)font ParagraphStyle:(NSMutableParagraphStyle *)style constrainedToWidth:(CGFloat)width
{
    
    CGRect rect;
    CGFloat height;
    
    CGRect textRect=[text boundingRectWithSize:CGSizeMake(width, MAXFLOAT)  options:NSStringDrawingUsesLineFragmentOrigin | NSStringDrawingUsesFontLeading  context:nil];
    
    //文本的高度减去字体高度小于等于行间距，判断为当前只有1行
    if ((textRect.size.height - font.lineHeight) <= style.lineSpacing)
    {
        
        if ([self containChinese:text.string])//如果包含中文
        {
            rect = CGRectMake(textRect.origin.x, textRect.origin.y, textRect.size.width, textRect.size.height-style.lineSpacing);
            height = rect.size.height;
        }
        else
        {
            height = textRect.size.height;
        }
        
        
    }
    else
    {
        height = textRect.size.height;
    }
    
    return height;
    
}

调用

    NSMutableAttributedString *attributeString = [[NSMutableAttributedString alloc] initWithString:string];
    
    NSMutableParagraphStyle *style = [[NSMutableParagraphStyle alloc] init];
    
    style.lineSpacing =10;
    [attributeString addAttribute:NSParagraphStyleAttributeName value:style range:NSMakeRange(0, string.length)];
    
    [attributeString addAttribute:NSFontAttributeName value:_titleLab.font range:NSMakeRange(0, string.length)];
    
    CGFloat height2 = [self HeightWithAttributedString:attributeString andFont:_titleLab.font ParagraphStyle:style constrainedToWidth:SCREEN_WIDTH];
    
    [_titleLab updateConstraints:^(MASConstraintMaker *make) {
        
        make.height.equalTo(@(height2 + 5));
    }];
    
    [_titleLab setAttributedText:attributeString];

判断字符串是否含有中文

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

富文本颜色

#pragma mark ************** 富文本
- (void)ParagraphStyle:(NSString *)priceStr Count:(NSString *)count TotalPrice:(NSString *)totalPrice Lab:(UILabel *)lab
{
    NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc] init];
    paragraphStyle.lineSpacing = 4.0f;// 行间距
    NSDictionary *ats = @{NSParagraphStyleAttributeName : paragraphStyle};
    NSMutableAttributedString *priceString = [[NSMutableAttributedString alloc] initWithString:priceStr attributes:ats];
    [priceString addAttribute:NSForegroundColorAttributeName
                        value:defaultColor
                        range:[priceStr rangeOfString:totalPrice]];
    [priceString addAttribute:NSForegroundColorAttributeName
                        value:defaultColor
                        range:[priceStr rangeOfString:count]];
    lab.attributedText = priceString;
    lab.textAlignment = NSTextAlignmentRight;
}