转换日期格式 年／月／日 ／星期

  NSDateFormatter *timeFormatter = [NSDateFormatter
new];
  [timeFormatter setDateStyle:NSDateFormatterFullStyle];
  NSLocale *locale = [[NSLocale
alloc] initWithLocaleIdentifier:@"zh"];
  [timeFormatter setLocale:locale];
  timeFormatter.dateFormat = @"yyyy/MM/dd EEE";
    NSString * str= [timeFormatter
stringFromDate: NSDate * date = [NSDate
date];
];