我是iOS開發新手,這裏是我的第一個應用程序計算器, 但NSMuteableArray「_numberArrayWaitingForCalculate」總是「無」,我不知道該怎麼辦?NSMutableArray addObject是否爲零?
這裏是接口
@interface demoViewController()
@property (strong,nonatomic)NSString *valueString;
@property (strong,nonatomic)NSMutableArray *numberArrayWaitingForCalculate;
@end
這裏器具1
@implementation demoViewController
@synthesize numberArrayWaitingForCalculate=_numberArrayWaitingForCalculate;
- (NSMutableArray *)numberWaitingForCalculate
{
if(!_numberArrayWaitingForCalculate)
_numberArrayWaitingForCalculate=[[NSMutableArray alloc]init];
return _numberArrayWaitingForCalculate;
}
這裏是tapNumber方法
- (IBAction)tapNumber:(UIButton *)numberButton {
if(LastButtonWasMode)
{
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LastButtonWasMode=NO;
}
NSString *numberAsString = numberButton.currentTitle;
_valueString=[_valueString stringByAppendingString:numberAsString];
result.text=[NSString stringWithFormat:@"%@",_valueString];
}
這裏是tapPlus方法
- (IBAction)tapPlus:(id)sender {
[_numberArrayWaitingForCalculate addObject:[NSNumber numberWithInt:[_valueString intValue]]];
resultOfAllNumberInputBefore +=[_valueString intValue];
[self setMode:1];
}
對指向數組的實例變量使用延遲初始化毫無意義,正如您發現的那樣,它是脆弱的。只需在您指定的初始化程序中初始化數組並完成它。 – bbum