objective-c-prefix属性必须后跟接口或协议栈溢出

[编译器错误]前缀属性必须后跟接口或协议堆栈溢出

代码在prev中运行良好.项目.发布这么简单的问题我觉得自己像个白痴.这东西怎么了？

#import <UIKit/UIKit.h>
#import "FlipsideViewController.h"

@interface MainViewController : UIViewController <FlipsideViewControllerDelegate>
<UIPickerViewDelegate><UIPickerViewDataSource>

@property (strong, nonatomic) IBOutlet UITextField *inputText;
@property(strong, nonatomic) IBOutlet UIPickerView *picker;
@property(strong, nonatomic) IBOutlet UILabel *resultLabel;
@property(strong, nonatomic) NSArray *_convertFrom;
@property(strong, nonatomic) NSArray *_convertTo;
@property(strong, nonatomic) NSArray *_convertRates;
@property(strong, nonatomic) IBOutlet UILabel *formelLabel;
@property(strong, nonatomic) IBOutlet UITextField *inputText;


-(IBAction)textFieldReturn:(id)sender;
-(IBAction)backgroundTouched:(id)sender;


@end

您声明对多个协议的确认,如下所示：

@interface MainViewController : UIViewController <FlipsideViewControllerDelegate, UIPickerViewDelegate, UIPickerViewDataSource>

没有多个尖括号套装.