將字符串轉換爲日期並找出時差

Question

我想將字符串轉換爲日期時間對象，然後減去2個日期之間的差異。不過，我不斷收到一個無效的指針警告。日期格式爲20131209 02:34。我的代碼如下

NSDateFormatter *df =[[NSDateFormatter alloc]init]; 
[df setDateFormat:@"YYYYMMDD HH:MM"]; 
NSDate *currTime = [df dateFromString:self.currentTime]; 
NSDate *predicTime =[df dateFromString:self.predictedTime]; 
NSTimeInterval newtime=[predicTime timeIntervalSinceDate:currTime]; 

Answer 1

您的日期格式是不正確的[df setDateFormat:@"YYYYMMDD HH:MM"];我假設你的字符串是有效的！

嘗試：

NSDateFormatter *df =[[NSDateFormatter alloc]init]; 
[df setDateFormat:@"yyyyMMdd HH:mm"]; // 24hr format, for 12hr format use 'hh' 
NSDate *currTime = [df dateFromString:@"20131209 02:34"]; 
NSDate *predicTime =[df dateFromString:@"20131209 04:34"]; 
NSTimeInterval newtime=[predicTime timeIntervalSinceDate:currTime]; 

Answer 2

嘗試這個代碼

NSDateFormatter *df =[[NSDateFormatter alloc]init]; 
[df setDateFormat:@"yyyyMMdd hh:mm"]; 
NSDate *currTime = [df dateFromString:self.currentTime]; 
NSDate *predicTime =[df dateFromString:self.predictedTime]; 
NSTimeInterval newtime=[predicTime timeIntervalSinceDate:currTime];