我是 iPhone 编程的另一个菜鸟，我有一个非常基本的问题，我无法回答。
首先，我在 xcode 3.1.4 中编写代码，以便我可以在旧平台上学习基础知识，并希望在不久的将来这将使我能够创建便携式应用程序（从某种意义上说，我将支持 iPhone 3以及）。不幸的是，据我了解，苹果已经剥离了 xcode 3.1.4 附带的文档，这使得很难猜测什么是正确的做事方式，因为当前的文档和示例建议的路由与 iOS 5 更相关（例如故事板）。因此，即使我似乎理解了 MVC 的整个概念，并且虽然我的第一个真正的玩具应用程序实际上正在运行，但它肯定没有正确管理内存，因为没有使用相关的 dealloc 方法（我拥有的相关 NSLogs 没有显示）。
现在具体说。我想创建一个单窗口应用程序（多边形，作业 3）。让我们忘记界面构建器；所有视图/子视图都将以编程方式创建。为此，我创建了一个自定义 UIViewController。我还创建了一个自定义 UIView 来描述我想要呈现的单个视图的自定义子视图。（很可能我们已经不同意我在这里的方法，但现在我真的相信我在这里尝试的东西在概念上是正确的）。在应用程序委托 (.h) 中，我声明了我的 mainController，这就是我真正声明的全部内容。该文件如下：
#import <UIKit/UIKit.h>
#import "MainViewController.h"
@interface MySimpleHelloPolyAppDelegate : NSObject <UIApplicationDelegate> {
UIWindow *window;
MainViewController * mainController;
}
@property (nonatomic, retain) IBOutlet UIWindow * window;
@property (nonatomic, assign) IBOutlet MainViewController * mainController;
@end
在运行时，我希望 mainController 为呈现给用户的主视图分配必要的内存，并添加我的自定义 UIView 的子视图（这将是绘制多边形的画布）。因此，本质上我想将窗口视为一个容器，mainController 的视图实际上向用户呈现主视图，并且我还将附加一个带有我们自定义画布实例（自定义视图）的子视图。下面是 AppDelegate.m 文件：
#import "MySimpleHelloPolyAppDelegate.h"
@implementation MySimpleHelloPolyAppDelegate
@synthesize window, mainController;
- (void)applicationDidFinishLaunching:(UIApplication *)application {
[window setBackgroundColor:[UIColor blueColor]]; // I do not want to see 'blue' on runtime
// On the creation of the MainViewController subclass I indicated that I want a nib for my new controller
// simply because this is the recommended way by apple. Apparently this should be an overkill for a simple
// one-window app, but nevertheless it should be ok.
mainController = [[MainViewController alloc] initWithNibName:nil bundle:nil];
[window addSubview:mainController.view];
[window makeKeyAndVisible];
}
- (void)dealloc {
NSLog(@"(AppDelegate): Dealloc is called");
[mainController.view removeFromSuperview];
[mainController release];
[window release];
[super dealloc];
}
@end
让我们看看 MainViewController.h：
#import <UIKit/UIKit.h>
#import "Polygon.h"
#import "Canvas.h"
@interface MainViewController : UIViewController {
IBOutlet UILabel * numSidesTextLabel;
IBOutlet UILabel * numSidesValueLabel;
IBOutlet UILabel * advancedOptionsLabel;
IBOutlet UILabel * polygonNameLabel;
IBOutlet UISwitch * advancedOptionsSwitch; // Not supported yet
IBOutlet UIButton * increaseButton;
IBOutlet UIButton * decreaseButton;
IBOutlet Canvas * myCanvas;
Polygon * myPolygon;
}
@property (nonatomic, retain) IBOutlet UILabel * numSidesTextLabel;
@property (nonatomic, retain) IBOutlet UILabel * numSidesValueLabel;
@property (nonatomic, retain) IBOutlet UIButton * increaseButton;
@property (nonatomic, retain) IBOutlet UIButton * decreaseButton;
@property (nonatomic, retain) IBOutlet UIView * myCanvas;
@property (nonatomic, retain) IBOutlet Polygon * myPolygon;
- (IBAction) increase;
- (IBAction) decrease;
- (void) updateInterface;
@end
现在让我们看看 MainViewController.m：
#import "MainViewController.h"
@implementation MainViewController
@synthesize numSidesTextLabel, numSidesValueLabel, decreaseButton, increaseButton, myCanvas, myPolygon;
- (IBAction) decrease {
[myPolygon setNumberOfSides:([myPolygon numberOfSides]-1)];
[self updateInterface];
}
- (IBAction) increase {
[myPolygon setNumberOfSides:([myPolygon numberOfSides]+1)];
[self updateInterface];
}
- (void) updateInterface {
int sides = [myPolygon numberOfSides];
UIColor * myOceanColor = [UIColor colorWithRed:0.00 green:0.333 blue:0.557 alpha:1.00];
[increaseButton setTitleColor:myOceanColor forState:UIControlStateNormal];
[increaseButton setTitleColor:[UIColor darkGrayColor] forState:UIControlStateDisabled];
[decreaseButton setTitleColor:myOceanColor forState:UIControlStateNormal];
[decreaseButton setTitleColor:[UIColor darkGrayColor] forState:UIControlStateDisabled];
numSidesValueLabel.text = [NSString stringWithFormat:@"%d", sides];
decreaseButton.enabled = YES; increaseButton.enabled = YES;
if (sides == MAX_NUM_SIDES_CONSTANT) increaseButton.enabled = NO;
else if (sides == MIN_NUM_SIDES_CONSTANT) decreaseButton.enabled = NO;
[myCanvas updateState:sides withName:[myPolygon name]];
[myCanvas setNeedsDisplay];
}
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil {
if (self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil]) {
// Custom initialization
}
return self;
}
- (void)loadView {
self.view = [[UIView alloc] initWithFrame:CGRectMake(0.0, 20.0, 320.0, 460.0)];
self.view.backgroundColor = [UIColor whiteColor];
}
- (void)viewDidLoad {
CGRect tempFrame;
UIColor * oceanColor = [UIColor colorWithRed:0.000 green:0.333 blue:0.557 alpha:1.000];
// Draw the labels
tempFrame = CGRectMake(20.0, 20.0, 150.0, 20.0);
numSidesTextLabel = [[UILabel alloc] initWithFrame:tempFrame];
numSidesTextLabel.text = @"Number of sides:";
numSidesTextLabel.textAlignment = UITextAlignmentLeft;
[self.view addSubview:numSidesTextLabel];
[numSidesTextLabel release];
tempFrame = CGRectMake(160.0, 20.0, 40.0, 20.0);
numSidesValueLabel = [[UILabel alloc] initWithFrame:tempFrame];
numSidesValueLabel.text = @"-----";
numSidesValueLabel.textAlignment = UITextAlignmentLeft;
[self.view addSubview:numSidesValueLabel];
[numSidesValueLabel release];
tempFrame = CGRectMake(20.0, 125.0, 160.0, 20.0);
advancedOptionsLabel = [[UILabel alloc] initWithFrame:tempFrame];
advancedOptionsLabel.text = @"Advanced options";
advancedOptionsLabel.textAlignment = UITextAlignmentLeft;
[self.view addSubview:advancedOptionsLabel];
[advancedOptionsLabel release];
// Draw the advanced switch
tempFrame = CGRectMake(205.0, 120.0, 120.0, 60.0);
advancedOptionsSwitch = [[UISwitch alloc] initWithFrame:tempFrame];
[advancedOptionsSwitch setOn:NO animated:YES];
[self.view addSubview:advancedOptionsSwitch];
[advancedOptionsSwitch release];
// Decrease Button
decreaseButton = [UIButton buttonWithType:UIButtonTypeRoundedRect]; // autoreleased
[decreaseButton setTitle:@"Decrease" forState:UIControlStateNormal];
[decreaseButton setTitleColor:oceanColor forState:UIControlStateNormal];
[decreaseButton setTitleColor:[UIColor darkGrayColor] forState:UIControlStateDisabled];
decreaseButton.frame = CGRectMake(20.0, 60.0, 110.0, 40.0);
[decreaseButton addTarget:self action:@selector(decrease) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:decreaseButton];
// Increase Button
increaseButton = [UIButton buttonWithType:UIButtonTypeRoundedRect]; // autoreleased
[increaseButton setTitle:@"Increase" forState:UIControlStateNormal];
[increaseButton setTitleColor:oceanColor forState:UIControlStateNormal];
[increaseButton setTitleColor:[UIColor darkGrayColor] forState:UIControlStateDisabled];
increaseButton.frame = CGRectMake(190.0, 60.0, 110.0, 40.0);
[increaseButton addTarget:self action:@selector(increase) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:increaseButton];
// Initialize the polygon
myPolygon = [[Polygon alloc] init];
numSidesValueLabel.text = [NSString stringWithFormat:@"%d", [myPolygon numberOfSides]];
// Prepare the canvas
CGRect myCanvasFrame = CGRectMake(20.0, 160.0, 280.0, 280.0);
myCanvas = [[Canvas alloc] initWithFrame:myCanvasFrame withNumSides:[myPolygon numberOfSides] withPolygonName:[myPolygon name]];
[self.view addSubview:myCanvas];
[myCanvas release];
[super viewDidLoad];
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
}
- (void)viewDidUnload {
// Release any retained subviews of the main view.
// e.g. self.myOutlet = nil;
numSidesTextLabel = nil;
numSidesValueLabel = nil;
advancedOptionsLabel = nil;
myPolygon = nil;
myCanvas = nil;
[self.view release]; self.view = nil;
}
- (void)dealloc {
NSLog(@"(MainViewController): Dealloc is called");
[numSidesTextLabel removeFromSuperview];
[numSidesValueLabel removeFromSuperview];
[advancedOptionsLabel removeFromSuperview];
[myPolygon release];
[myCanvas removeFromSuperview]; // This should generate additional output
[super dealloc];
}
@end
现在让我们看一下 Canvas.h 文件：
#import <UIKit/UIKit.h>
#import "PrepDefs.h"
@interface Canvas : UIView {
IBOutlet UILabel * polygonNameLabel;
int currentStateNumSides;
CGPoint center;
}
@property (nonatomic, retain) UILabel * polygonNameLabel;
@property (nonatomic, assign) int currentStateNumSides;
@property (nonatomic, assign) CGPoint center;
+ (NSArray *) pointsForPolygonInRect:(CGRect) rect numberOfSides:(int) numberOfSides;
- (id) initWithFrame:(CGRect)frame withNumSides:(int)sides withPolygonName:(NSString *) name;
- (void) updateState:(int)sides withName:(NSString *)name;
@end
Canvas.m 文件：
#import "Canvas.h"
@implementation Canvas
@synthesize polygonNameLabel, currentStateNumSides, center;
+ (NSArray *) pointsForPolygonInRect:(CGRect)rect numberOfSides:(int)numberOfSides {
CGPoint center = CGPointMake(rect.size.width / 2.0, rect.size.height / 2.0);
float radius = 0.9 * center.x;
NSMutableArray *result = [NSMutableArray array];
float angle = (2.0 * M_PI) / numberOfSides;
float exteriorAngle = M_PI - angle;
float rotationDelta = angle - (0.5 * exteriorAngle);
for (int currentAngle = 0; currentAngle < numberOfSides; currentAngle++) {
float newAngle = (angle * currentAngle) - rotationDelta;
float curX = cos(newAngle) * radius;
float curY = sin(newAngle) * radius;
[result addObject:[NSValue valueWithCGPoint:CGPointMake(center.x + curX, center.y + curY)]];
}
return result;
}
- (id) initWithFrame:(CGRect)frame withNumSides:(int)sides withPolygonName:(NSString *)name {
if (self = [super initWithFrame:frame]) {
// Initialization code
[self setBackgroundColor:[UIColor brownColor]];
currentStateNumSides = sides;
center = CGPointMake ([self bounds].size.width / 2.0, [self bounds].size.height / 2.0);
polygonNameLabel = [[UILabel alloc] initWithFrame:CGRectMake(0.0, center.y - 10.0, [self bounds].size.width, 20.0)];
polygonNameLabel.text = name;
polygonNameLabel.textAlignment = UITextAlignmentCenter;
polygonNameLabel.backgroundColor = [UIColor clearColor];
[self addSubview:polygonNameLabel];
[polygonNameLabel release];
}
return self;
}
- (id)initWithFrame:(CGRect)frame {
NSLog(@"(Canvas, -initWithFrame): You should always use initWithFrame:withNumSides:withPolygonName:");
return [self initWithFrame:frame withNumSides:DEFAULT_NUM_SIDES withPolygonName:DEFAULT_POLYGON_NAME];
}
- (void)drawRect:(CGRect)rect {
// Drawing code
NSArray * points = [Canvas pointsForPolygonInRect:[self bounds] numberOfSides:[self currentStateNumSides]];
CGContextRef currentContext = UIGraphicsGetCurrentContext();
[[UIColor blackColor] set];
UIRectFrame ([self bounds]);
CGContextBeginPath (currentContext);
for (int i = 0; i < [points count]; i++) {
CGPoint currentPoint;
NSValue * currentValue;
currentValue = [points objectAtIndex:i];
currentPoint = [currentValue CGPointValue];
//NSLog(@"(%.1f, %.1f)", currentPoint.x, currentPoint.y);
if (i == 0)
CGContextMoveToPoint(currentContext, currentPoint.x, currentPoint.y);
else
CGContextAddLineToPoint(currentContext, currentPoint.x, currentPoint.y);
}
CGContextClosePath(currentContext);
[[UIColor yellowColor] setFill];
[[UIColor blackColor] setStroke];
CGContextDrawPath(currentContext, kCGPathFillStroke);
}
- (void) updateState:(int)sides withName:(NSString *)name {
currentStateNumSides = sides;
polygonNameLabel.text = name;
}
- (void)dealloc {
NSLog(@"(Canvas): Calling dealloc");
[polygonNameLabel removeFromSuperview]; polygonNameLabel = nil;
[super dealloc];
}
@end
PrepDefs.h 文件：
#ifndef __PREP_DEFS_H__
#define __PREP_DEFS_H__
#define MIN_NUM_SIDES_CONSTANT 3
#define DEFAULT_NUM_SIDES 5
#define MAX_NUM_SIDES_CONSTANT 12
#define DEFAULT_POLYGON_NAME @"Pentagon"
#endif
最后是 Polygon 类的文件。Polygon.h 文件：
#import <Foundation/Foundation.h>
#import "PrepDefs.h"
@interface Polygon : NSObject {
int numberOfSides;
int minimumNumberOfSides;
int maximumNumberOfSides;
}
@property int numberOfSides;
@property int minimumNumberOfSides;
@property int maximumNumberOfSides;
@property (readonly) float angleInDegrees;
@property (readonly) float angleInRadians;
@property (readonly) NSString * name;
- (void) setNumberOfSides:(int)numSides;
- (void) setMinimumNumberOfSides:(int)minNumSides;
- (void) setMaximumNumberOfSides:(int)maxNumSides;
- (id) initWithNumberOfSides:(int)sides minimumNumberOfSides:(int)min maximumNumberOfSides:(int)max;
@end
Polygon.m 文件：
#import "Polygon.h"
@implementation Polygon
@synthesize numberOfSides, minimumNumberOfSides, maximumNumberOfSides, angleInDegrees, angleInRadians, name;
- (void) setNumberOfSides:(int)numSides {
if ((numSides >= [self minimumNumberOfSides]) && (numSides <= [self maximumNumberOfSides])) numberOfSides = numSides;
else NSLog(@"PolygonShape [setNumberOfSides]: Assignment out of bounds");
}
- (void) setMinimumNumberOfSides:(int)minNumSides {
if (minNumSides >= MIN_NUM_SIDES_CONSTANT) minimumNumberOfSides = minNumSides;
else NSLog(@"PolygonShape [setMinimumNumberOfSides]: Assignment out of bounds");
}
- (void) setMaximumNumberOfSides:(int)maxNumSides {
if (maxNumSides <= MAX_NUM_SIDES_CONSTANT) maximumNumberOfSides = maxNumSides;
else NSLog(@"PolygonShape [setMaximumNumberOfSides]: Assignment out of bounds");
}
- (float) angleInDegrees {
int sides = [self numberOfSides];
return ((float) (180.0 * ((double) (sides - 2)) / ((double) sides)));
}
- (float) angleInRadians {
int sides = [self numberOfSides];
return ((double) M_PI) * ((double) (sides - 2.0)) / ((double) sides);
}
- (NSString *) name {
NSString * s;
switch ([self numberOfSides]) {
case 3: s = [NSString stringWithString:@"Triangle"]; break;
case 4: s = [NSString stringWithString:@"Square"]; break;
case 5: s = [NSString stringWithString:@"Pentagon"]; break;
case 6: s = [NSString stringWithString:@"Hexagon"]; break;
case 7: s = [NSString stringWithString:@"Heptagon"]; break;
case 8: s = [NSString stringWithString:@"Octagon"]; break;
case 9: s = [NSString stringWithString:@"Enneagon"]; break;
case 10: s = [NSString stringWithString:@"Decagon"]; break;
case 11: s = [NSString stringWithString:@"Hendecagon"]; break;
case 12: s = [NSString stringWithString:@"Dodecagon"]; break;
default: NSLog(@"PolygonShape [name]: I should never enter here."); s = nil; break;
}
return s;
}
- (id) init {
return [self initWithNumberOfSides:DEFAULT_NUM_SIDES minimumNumberOfSides:MIN_NUM_SIDES_CONSTANT maximumNumberOfSides:MAX_NUM_SIDES_CONSTANT];
}
- (id) initWithNumberOfSides:(int)sides minimumNumberOfSides:(int)min maximumNumberOfSides:(int)max {
if (self = [super init]) {
// Cautiously initialize everything to zero
numberOfSides = 0;
minimumNumberOfSides = 0;
maximumNumberOfSides = 0;
// Attempt the actual assignment
[self setMaximumNumberOfSides:max];
[self setMinimumNumberOfSides:min];
[self setNumberOfSides:sides];
}
return self;
}
- (NSString *) description {
return [NSString stringWithFormat:@"Hello I am a %d-sided polygon (aka a %@) with angles of %.3f degrees (%.6f radians)", [self numberOfSides], [self name], [self angleInDegrees], [self angleInRadians]];
}
- (void) dealloc {
NSLog(@"(Polygon): Dealloc is called");
[super dealloc];
}
@end
综上所述，我认为问题是：
- 为什么不使用dealloc函数？我实际上在哪里有泄漏？
- 当我初始化我的 mainController 时，我是否应该将我在为 mainController 创建自定义类时创建的 nib 文件的名称作为参数传递？
- 我应该以不同的方式初始化 mainController 及其视图吗？
- 我应该使用 awakeFromNib 而不是 loadView 或 viewDidLoad？
- 您对整个方法还有其他意见吗？例如单屏应用程序的好或坏编程实践？这确实是一个小程序，所以，我相信这不是一个开放式的问题。但是，如果您认为这是一个开放式问题，请不要回答。这可能是一个菜鸟对一些老手提出的一个幼稚的问题。
我非常感谢您为此花费的所有时间，并期待您的反馈。