单击下一个和上一个 UIButton 时更改 UILabel 中的日期

Question

在 UILabel 中设置一个日期。单击 "next" 和 "previous" 按钮应该会更改此标签内的日期。

我正在尝试此代码，但单击下一个按钮并显示第二天的日期，例如 01/05/2015 和上一个按钮单击并设置日期 29/05/2015 和下一个按钮单击不显示 02/05/ 2015

- (IBAction)changeToNextDay:(id)sender
{
    NSDateComponents* deltaComps = [[NSDateComponents alloc] init];
    [deltaComps setDay:+1];
    NSDate* tomorrow = [[NSCalendar currentCalendar]  dateByAddingComponents:deltaComps toDate:[NSDate date] options:0];

    NSDateFormatter *myDateFormatter = [[NSDateFormatter alloc] init];
    [myDateFormatter setDateFormat:@"dd-MM-yyyy"];

    NSString *stringFromDate = [myDateFormatter  stringFromDate:tomorrow];
    dateLabel.text = stringFromDate;
}

- (IBAction)changeToPreviousDay:(id)sender
{
    NSDate *datePlusOneDay = [[NSDate date] dateByAddingTimeInterval:-(60 * 60 * 24)];
    NSLog(@"datePlusOneDay=%@",datePlusOneDay);

    NSDateFormatter *myDateFormatter = [[NSDateFormatter alloc] init];
    [myDateFormatter setDateFormat:@"dd-MM-yyyy"];

    NSString *stringFromDate = [myDateFormatter stringFromDate:datePlusOneDay];
    dateLabel.text = stringFromDate;
}

Answer 1

前一天的函数

-(void)previousDay
{
  NSDate *today = [NSDate date];
    NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init];
    [dateFormat setDateFormat:@"dd/MM/yyyy"];
    dateString = [dateFormat stringFromDate:today];


    NSCalendar *calendar = [NSCalendar currentCalendar];
    NSDateComponents *comps = [NSDateComponents new];
    comps.day =-1;
    NSDate *previousDay = [calendar dateByAddingComponents:comps toDate:[NSDate date] options:0];
    [dateFormat setDateFormat:@"dd/MM/yyyy"];
    resultDate = [dateFormat stringFromDate:previousDay];

}

第二天函数

-(void)nextDay
{
  NSDate *today = [NSDate date];
    NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init];
    [dateFormat setDateFormat:@"dd/MM/yyyy"];
    dateString = [dateFormat stringFromDate:today];


    NSCalendar *calendar = [NSCalendar currentCalendar];
    NSDateComponents *comps = [NSDateComponents new];
    comps.day =1;
    NSDate *nextDay = [calendar dateByAddingComponents:comps toDate:[NSDate date] options:0];
    [dateFormat setDateFormat:@"dd/MM/yyyy"];
    resultDate = [dateFormat stringFromDate:nextDay];;

}

你可以使用这个功能

Answer 2

- (void)viewDidLoad {
    [super viewDidLoad];
    [self Update_Date_By:0];
}

- (IBAction)changeToNextDay:(id)sender {
    [self Update_Date_By:1];
}

- (IBAction)changeToPreviousDay:(id)sender {
    [self Update_Date_By:-1];
}

-(void)Update_Date_By:(NSInteger)value {
    NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init];
    [dateFormat setDateFormat:@"dd/MM/yyyy"];
    NSDate *date = [dateFormat dateFromString:dateLabel.text];
    NSCalendar *calendar = [NSCalendar currentCalendar];
    NSDateComponents *dateComponents = [NSDateComponents new];
    dateComponents.day = value;
    if (value == 0) {
        date = [NSDate date];
    }
    NSDate *newDate = [calendar dateByAddingComponents:dateComponents toDate:date options:0];
    [dateFormat setDateFormat:@"dd/MM/yyyy"];
    NSString *finalDate_String = [dateFormat stringFromDate:newDate];
    dateLabel.text = finalDate_String;
}

Answer 3

您可以通过简单的 way.Follow 步骤实现此操作-

声明两个全局变量，用于格式化和递增或递减 date.Such as-

#import "ViewController.h"

@interface ViewController ()
{
```
NSDateFormatter *DateFormatter;
int day;
```
}
```
@end
```

在viewDidLoad中，定义日期的格式，在UILabel中设置当前日期，并初始化day变量为0-

day=0;
DateFormatter=[[NSDateFormatter alloc] init];
[DateFormatter setDateFormat:@"dd/MM/yyyy"];
dateLabel.text=[DateFormatter stringFromDate:[NSDate date]];

为了去第二天把代码写在'changeToNextDay'按钮的body-

NSDate *now = [NSDate date];
day+=1;
NSDateComponents *components =[[NSDateComponents alloc] init];
[components setDay:day];
 NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSCalendarIdentifierGregorian];  
 NSDate *newDate = [gregorian dateByAddingComponents:components toDate:now options:0];
 dateLabel.text=[DateFormatter stringFromDate:newDate];

要转到前一天，只需从 'changeToNextDay' 复制代码并将其粘贴到 'changeToPreviousDay' 按钮并更改行 -
```
 day-=1 from day+=1;
```

让我知道它是否适合 you.Thank 你。

单击下一个和上一个 UIButton 时更改 UILabel 中的日期

Change date in UILabel when click next and previous UIButton

objective-c

updates

nsdate

uilabel

ios