根据NSString 转化为 NSDate , 进而根据NSDate 计算年龄

//根据string 转化为 nsdate  , 进而 根据nsdate 计算年龄#import <Foundation/Foundation.h>@interface NSDate (Extension)+ (NSInteger)ageWithDateOfBirth:(NSDate *)date;+ (NSDate *)dateFromString:(NSString *)string;@end#import "NSDate+Extension.h"@implementation NSDate (Extension)+ (NSInteger)ageWithDateOfBirth:(NSDate *)date;{    // 出生日期转换 年月日    NSDateComponents *components1 = [[NSCalendar currentCalendar] components:NSDayCalendarUnit | NSMonthCalendarUnit | NSYearCalendarUnit fromDate:date];    NSInteger brithDateYear  = [components1 year];    NSInteger brithDateDay   = [components1 day];    NSInteger brithDateMonth = [components1 month];        // 获取系统当前 年月日    NSDateComponents *components2 = [[NSCalendar currentCalendar] components:NSDayCalendarUnit | NSMonthCalendarUnit | NSYearCalendarUnit fromDate:[NSDate date]];    NSInteger currentDateYear  = [components2 year];    NSInteger currentDateDay   = [components2 day];    NSInteger currentDateMonth = [components2 month];        // 计算年龄    NSInteger iAge = currentDateYear - brithDateYear - 1;    if ((currentDateMonth > brithDateMonth) || (currentDateMonth == brithDateMonth && currentDateDay >= brithDateDay)) {        iAge++;    }        return iAge;}+ (NSDate *)dateFromString:(NSString *)string{    //字符串转nsdate    NSDateFormatter *inputFormatter = [[NSDateFormatter alloc] init];    //dateFormat 根据数据修改格式    [inputFormatter setDateFormat:@"yyyy/MM/dd"];    NSDate *date = [inputFormatter dateFromString:string];    return date;}@end