Creating Your First Mac AppReviewing the Code 审查代码

Reviewing the Code

If you have trouble getting your app to work correctly, compare your code with the listings shown at the end of this chapter and review your action and outlet connections.

如果你的应用程序运行不正确，重新对照本章结尾处的代码列表，审查你的动作(action)和接口(outlet)连接是否正确。

Code and Compiler Warnings

代码 和编译器警告(Warnings)

Your code should compile without any warnings. If you do receive warnings, it’s recommended that you treat them as likely to be errors. Because Objective-C is a flexible language, sometimes the most you get from the compiler is a warning.

你的代码编译应该不会出现任何警告。如果出现了警告，我们推荐你像对待错误(errors)一样对待它们。因为Objective-C 是一种灵活的语言(flexible language), 有时候你从编译器得到最多的就是一条警告。

Code Listings

This section provides listings for the interface and implementation files of the AppDelegate and Track classes. These listings don’t show comments and other method implementations that are provided by the Xcode template.

本节提供AppDelegate 和 Track 类的 接口(interface)和实现文件(implementation files)代码。 这些代码不包括注释 和 由Xcode模板提供的其它实现方法。

The Interface File: AppDelegate.h

接口文件：AppDelegate.h

#import <Cocoa/Cocoa.h>

@class Track;

@interface AppDelegate : NSObject <NSApplicationDelegate>

@property (assign) IBOutlet NSWindow *window;

@property (weak) IBOutlet NSTextField *textField;

@property (weak) IBOutlet NSSlider *slider;

@property (strong) Track *track;

- (IBAction)mute:(id)sender;

- (IBAction)takeFloatValueForVolumeFrom:(id)sender;

- (void)updateUserInterface;

@end

The Implementation File: AppDelegate.m

实现文件：AppDelegate.m

#import "AppDelegate.h"

#import "Track.h"

@implementation AppDelegate

@synthesize textField = _textField;

@synthesize slider = _slider;

- (void)applicationDidFinishLaunching:(NSNotification *)aNotification

{

    Track *aTrack = [[Track alloc] init];

    [self setTrack:aTrack];

    [self updateUserInterface];

}

- (IBAction)mute:(id)sender {

    [self.track setVolume:0.0];

    [self updateUserInterface];

}

- (IBAction)takeFloatValueForVolumeFrom:(id)sender {

    float newValue = [sender floatValue];

    [self.track setVolume:newValue];

    [self updateUserInterface];

}

- (void)updateUserInterface {

    float volume = [self.track volume];

    [self.textField setFloatValue:volume];

    [self.slider setFloatValue:volume];

}

@end

The Interface File: Track.h

#import <Foundation/Foundation.h>

@interface Track : NSObject

@property (assign) float volume;

@end

The Implementation File: Track.m

#import "Track.h"

@implementation Track

@end

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