ValueObject#import <Foundation/Foundation.h>@interface CurrentDataVO : NSObject@property (nonatomic, retain) NSString *crt;@property (nonatomic, retain) NSString *last;@property (nonatomic, retain) NSString *dataType;@property (nonatomic, retain) NSString *date;@property (nonatomic, retain) NSMutableArray *days;@property (nonatomic, retain) NSString *cv; - (void)showAllData;#import "CurrentDataVO.h"@implementation CurrentDataVO@synthesize crt;@synthesize last;@synthesize dataType;@synthesize date;@synthesize days;@synthesize cv; - (id)init {    self = [super init];    if (self) {         days = [[NSMutableArray alloc] init];     }    return self; } - (void)showAllData {    NSLog(@"%@", crt);    NSLog(@"%@", last);    NSLog(@"%@", dataType);    NSLog(@"%@", date);    NSLog(@"%@", cv);    NSLog(@"%@", days); }@endViewCtrlA[cell setContentData:todayData withYesData:vo.last];ViewCtrlB- (void)setContentData:(NSString *)todayData withYesData:(NSString *)yesData {    [todayDataLabel setText:todayData];    [yesDataLabel setText:yesData]; }cell不為nil在ViewCtrlB中 NSlog 能打印出 todayData，但是賦值到setText中時會拋出異常。2012-12-13 14:10:35.510 mbaforios[29723:fb03] 10052012-12-13 14:10:35.511 mbaforios[29723:fb03] -[__NSCFNumber isEqualToString:]: unrecognized selector sent to instance 0x6b904e02012-12-13 14:10:35.511 mbaforios[29723:fb03] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSCFNumber isEqualToString:]: unrecognized selector sent to instance 0x6b904e0'*** First throw call stack: (0x12f1022 0x17a2cd6 0x12f2cbd 0x1257ed0 0x1257cb2 0x46a0ff 0x7abd 0x440c 0x93d9 0xd2da49 0xd2be84 0xd2cea7 0xd2be3f 0xd2bfc5 0xc70f5a 0x1a52a39 0x1b1f596 0x1b1f861 0x1a49120 0x1b1f117 0x1a48fbf 0x12c594f 0x1228b43 0x1228424 0x1227d84 0x1227c9b 0x1fab7d8 0x1fab88a 0x32a626 0x2ad2 0x2a45) terminate called throwing an exception(lldb)