iOS 常用技巧

加载视图

viewDidLoad－加载视图
viewWillAppear－UIViewController对象的视图即将加入窗口时调用；
viewDidApper－UIViewController对象的视图已经加入到窗口时调用；
viewWillDisappear－UIViewController对象的视图即将消失、被覆盖或是隐藏时调用；
viewDidDisappear－UIViewController对象的视图已经消失、被覆盖或是隐藏时调用；
viewVillUnload－当内存过低时，需要释放一些不需要使用的视图时，即将释放时调用；
viewDidUnload－当内存过低，释放一些不需要的视图时调用。

找到当前控制器

- (UIViewController*)viewController {
    for (UIView *next = [self superview]; next; next = next.superview) {
        UIResponder* nextResponder = [next nextResponder];
        if ([nextResponder isKindOfClass:[UIViewController class]]) {
            
            return (UIViewController*)nextResponder;
        }
    }
    return nil;
}

时间戳转换时间

- (NSString *)timelineConversionTime:(NSString *)timeline{
    
    NSTimeInterval time=[timeline doubleValue]+28800;//因为时差问题要加8小时 == 28800 sec
    
    NSDate *detaildate=[NSDate dateWithTimeIntervalSince1970:time];
    
    NSLog(@"-----------date:%@",[detaildate description]);
    
    //实例化一个NSDateFormatter对象
    
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    
    //设定时间格式,这里可以设置成自己需要的格式
    
    [dateFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
    
    
    return [dateFormatter stringFromDate: detaildate];
}

将时间转换成秒

-(NSString *) getSecondsWithTime:(NSString *)time
{
    NSDateFormatter *formatter = [[NSDateFormatter alloc]init];
    [formatter setDateFormat:@"YYYY-MM-dd HH:mm:ss"];
    NSDate *date = [formatter dateFromString:time];
    NSString *timeStr = [NSString stringWithFormat:@"%ld",(long)[date timeIntervalSince1970]];
    
    return timeStr;
}

设置UILabel行间距

NSMutableParagraphStyle *style = [[NSMutableParagraphStyle alloc] init];
[style setLineSpacing:20];
[attrString addAttribute:NSParagraphStyleAttributeName value:style range:NSMakeRange(0, label.text.length)];
label.attributedText = attrString;

UILabel显示不同颜色字体

NSMutableAttributedString * string = [[NSMutableAttributedString alloc] initWithString:label.text];
[string addAttribute:NSForegroundColorAttributeName value:[UIColor redColor] range:NSMakeRange(0,5)];
[string addAttribute:NSForegroundColorAttributeName value:[UIColor greenColor] range:NSMakeRange(5,6)];
[string addAttribute:NSForegroundColorAttributeName value:[UIColor blueColor] range:NSMakeRange(11,5)];
label.attributedText = string;

比较两个NSDate相差多少小时

 NSDate* date1 = someDate;
 NSDate* date2 = someOtherDate;
 NSTimeInterval distanceBetweenDates = [date1 timeIntervalSinceDate:date2];
 double secondsInAnHour = 3600;
// 除以3600是把秒化成小时，除以60得到结果为相差的分钟数
 NSInteger hoursBetweenDates = distanceBetweenDates / secondsInAnHour;

判断一个字符串是否为数字

NSCharacterSet *notDigits = [[NSCharacterSet decimalDigitCharacterSet] invertedSet];
    if ([str rangeOfCharacterFromSet:notDigits].location == NSNotFound)
    {
      // 是数字
    } else
    {
      // 不是数字
    }

获取当前导航控制器下前一个控制器

- (UIViewController *)backViewController
    {
        NSInteger myIndex = [self.navigationController.viewControllers indexOfObject:self];

    if ( myIndex != 0 && myIndex != NSNotFound ) {
        return [self.navigationController.viewControllers objectAtIndex:myIndex-1];
    } else {
        return nil;
    }
}

判断一个字符串是否包含另一个字符串

// 方法一、这种方法只适用于iOS8之后，如果是配iOS8之前用方法二
if ([str containsString:otherStr]) NSLog(@"包含");

// 方法二
NSRange range = [str rangeOfString:otherStr];
if (range.location != NSNotFound) NSLog(@"包含");

让导航控制器pop回指定的控制器

NSMutableArray *allViewControllers = [NSMutableArray arrayWithArray:[self.navigationController viewControllers]];
for (UIViewController *aViewController in allViewControllers) {
    if ([aViewController isKindOfClass:[RequiredViewController class]]) {
        [self.navigationController popToViewController:aViewController animated:NO];
    }
}

地图上两个点之间的实际距离

CLLocation *location1 = [[CLLocation alloc] initWithLatitude:lat1 longitude:long1] ;
CLLocation *location2 = [[CLLocation alloc] initWithLatitude:lat2 longitude:long2];
CLLocationDistance kilometers = [location1 distanceFromLocation:location2];

页面跳转实现翻转动画

// modal方式
    TestViewController *vc = [[TestViewController alloc] init];
    vc.view.backgroundColor = [UIColor redColor];
    vc.modalTransitionStyle = UIModalTransitionStyleCoverVertical;
    [self presentViewController:vc animated:YES completion:nil];
 
// push方式
    TestViewController *vc = [[TestViewController alloc] init];
    vc.view.backgroundColor = [UIColor redColor];
    [UIView beginAnimations:@"View Flip" context:nil];
    [UIView setAnimationDuration:0.80];
    [UIView setAnimationCurve:UIViewAnimationCurveEaseInOut];
    [UIView setAnimationTransition:UIViewAnimationTransitionFlipFromRight forView:self.navigationController.view cache:NO];
    [self.navigationController pushViewController:vc animated:YES];
    [UIView commitAnimations];