小编she*_*ebi的帖子

在这里,我试图计算两个日期之间的小时数.当我运行应用程序时,它崩溃了.你能告诉我这段代码中的错误吗？

NSString *lastViewedString = @"2012-04-25 06:13:21 +0000";
NSDateFormatter *dateFormatter = [[[NSDateFormatter alloc] init] autorelease];
[dateFormatter setDateFormat: @"yyyy-MM-dd HH:mm:ss zzz"];

NSDate *lastViewed = [[dateFormatter dateFromString:lastViewedString] retain];
NSDate *now = [NSDate date];

NSLog(@"lastViewed: %@", lastViewed); //2012-04-25 06:13:21 +0000
NSLog(@"now: %@", now); //2012-04-25 07:00:30 +0000

NSTimeInterval distanceBetweenDates = [now timeIntervalSinceDate:lastViewed];
double secondsInAnHour = 3600;
NSInteger hoursBetweenDates = distanceBetweenDates / secondsInAnHour;

NSLog(@"hoursBetweenDates: %@", hoursBetweenDates);

我正在开发一个带有核心图表的iPhone应用程序.在一些教程的帮助下,我设法通过单点触摸和拖动来完成.如何通过多次触摸和拖动来实现？有人请帮帮我吗？

ViewController.m

- (void)viewDidLoad
{
    [super viewDidLoad];

    EskPlotTheme *defaultTheme = [[EskPlotTheme alloc] init];
    linePlot = [[EskLinePlot alloc] init];
    linePlot.delegate = self;
    [linePlot renderInLayer:lineHostingView withTheme:defaultTheme]; 
    [defaultTheme release];    
}

EskLinePlot.m

- (id)init
{
    self = [super init];
    if (self) 
    {
        // setting up the sample data here.
        sampleData = [[NSArray alloc] initWithObjects:[NSNumber numberWithInt:6000],
                                                      [NSNumber numberWithInt:3000],
                                                      [NSNumber numberWithInt:2000],
                                                      [NSNumber numberWithInt:5000],
                                                      [NSNumber numberWithInt:7000],
                                                      [NSNumber numberWithInt:8500],
                                                      [NSNumber numberWithInt:6500], nil];

    }
    return self;
}

- (void)renderInLayer:(CPTGraphHostingView *)layerHostingView withTheme:(CPTTheme *)theme
{
    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; …

对于我的新项目.我已将我的csv文件内容加载为NSString.首先,我需要通过换行拆分它,然后用逗号分隔每一行.我怎么能循环这一切？请你帮助我好吗？

CSV内容

"^ GSPC",1403.36,"4/27/2012","4:32 pm",+ 3.38,1400.19,1406.64,1397.31,574422720"^ IXIC",3069.20,"4/27/2012","5:30 pm " + 18.59,3060.34,3076.44,3043.30,0

ViewController.m

NSString* pathToFile = [[NSBundle mainBundle] pathForResource: @"quotes" ofType: @"csv"];
NSString *fileString = [NSString stringWithContentsOfFile:pathToFile encoding:NSUTF8StringEncoding error:nil];
if (!fileString) {
    NSLog(@"Error reading file.");
}

NSArray *array = [fileString componentsSeparatedByCharactersInSet:[NSCharacterSet newlineCharacterSet]];

for(int i=0; i<[array count]; i++){      
    //
}

我在我的项目中的两个视图控制器ViewController,SettingsView.我在这里尝试更新ViewController's标签,当我点击SettingsView's后退按钮时.NSLog工作正常,但标签没有更新......请帮帮我......

SettingsView.m

-(IBAction)backToMain:(id) sender {

  //calling update function from ViewController
    ViewController * vc = [[ViewController alloc]init];
    [vc updateLabel];
    [vc release];

  //close the SettingsView 
    [self dismissModalViewControllerAnimated:YES];
}

ViewController.m

- (void)updateLabel
{
    NSLog(@"Iam inside updateLabel");
   self.myLabel.text = @"test";
}

你能告诉我我的代码有什么问题吗？谢谢!

我正在使用Xcode 4.3.2,如何在每天早上6点设置本地通知"dateToFire"？

-(void)notification
{
    UILocalNotification *localNotification = [[[UILocalNotification alloc] init] autorelease];

    if (!localNotification) 
        return;

    // Current date
    NSDate *date = [NSDate date]; 
    NSDate *dateToFire = //Everyday: 6AM;

    // Set the fire date/time
    [localNotification setFireDate:dateToFire];
    [localNotification setTimeZone:[NSTimeZone defaultTimeZone]];
    [localNotification setAlertBody:@"Notification" ];      

    [[UIApplication sharedApplication] scheduleLocalNotification:localNotification];
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    [self notification];
}

我正在开发一个新的iPhone应用程序,在这里,我已经从本地解析了一个'csv'文件,并与我一起工作.当我尝试以编程方式从服务器下载'csv'文件时,它没有为我锻炼.请你帮助我好吗？

从本地文件加载数据(工作正常)

- (void)viewDidLoad
{  
    [super viewDidLoad];

    NSString * file = [[NSBundle bundleForClass:[self class]] pathForResource:@"sample" ofType:@"csv"];

    NSStringEncoding encoding = 0;
    NSString * csv = [NSString stringWithContentsOfFile:file usedEncoding:&encoding error:nil];
    NSArray *fields = [csv CSVComponents];
    NSLog(@"fields: %@", fields); //getting the result content 
}

从服务器下载文件(失败)

-(void) connectionDidFinishLoading:(NSURLConnection *)connection
{
    NSLog(@"connectionDidFinishLoading"); //nothing showing here

    NSString *docDir = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
    NSString *fullName = [NSString stringWithFormat:@"quotes.csv"];

    NSString *fullFilePath = [NSString stringWithFormat:@"%@/%@",docDir,fullName];
    [receivedData writeToFile:fullFilePath atomically:YES];
} 

-(void) connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
    NSLog(@"data: …

如何以编程方式更改UISegmentedControl标题？请你帮助我好吗？

@synthesize filterControl; //UISegmentedControl

- (void)viewDidLoad
{
    [super viewDidLoad];

    filterControl = [[UISegmentedControl alloc] initWithItems:[NSArray arrayWithObjects:@"ALL",@"PROFIT",@"LOSS", nil]]; //not working

}