一、例如：
NSString *ceShiStr = [self getWeekDay:@"2016-12-04"];
NSLog(@"ceShiStr = %@",ceShiStr);
打印结果 : 周日
- (NSString*)getWeekDay:(NSString*)currentStr
{
NSDateFormatter* dateFormat = [[NSDateFormatteralloc]init];//实例化一个NSDateFormatter对象
[dateFormatsetDateFormat:@"yyyy-MM-dd"];//设定时间格式,要注意跟下面的dateString匹配，否则日起将无效
NSDate*date =[dateFormatdateFromString:currentStr];
NSArray*weekdays = [NSArrayarrayWithObjects: [NSNullnull],@"周日",@"周一",@"周二",@"周三",@"周四",@"周五",@"周六",nil];
NSCalendar*calendar = [[NSCalendaralloc]initWithCalendarIdentifier:NSCalendarIdentifierGregorian];
NSTimeZone*timeZone = [[NSTimeZonealloc]initWithName:@"Asia/Shanghai"];
[calendarsetTimeZone: timeZone];
NSCalendarUnitcalendarUnit =NSCalendarUnitWeekday;
NSDateComponents*theComponents = [calendarcomponents:calendarUnitfromDate:date];
return[weekdaysobjectAtIndex:theComponents.weekday];
}
