UIImageView 和 UIWebView 小结

本文转载至：http://www.cnblogs.com/huangdongcheng/archive/2011/11/21.html

1.UIImageView的讲解

（1）初始化

UIImageView  *imageView = [[UIImageView alloc] initWithFrame:CGRectMake(0.0,45.0,300,300)];

imageView.image = [UIImage imageNamed:@"a.png"];//加载入图片

[self.view addSubView:image];

也可以这样声明：

UIImage *image = [[UIImage alloc] initWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:@"http://farm4.static.flickr.com/3092/2915896504_a88b69c9de.jpg"]]];
UIImageView *imageView = [[UIImageView alloc] initWithImage:image];

在加载入图片的时候有两种加载UIImage的方法：如下：

-》1

[UIImage imageNamed:@"a.png"];

-》2

NSString *path = [[NSBundle mainBundle] pathForResource:@”icon”
ofType:@”png”];
myImage = [UIImage imageWithContentsOfFile:path];

如果找到图片，装载到iPhone系统缓存图象。那意味图片是(理论上)放在内存里作为cache的。因此如果图片资源多了或大了，此方式容易引起发生内存警告从而导致自动退出的问题。

最好是通过直接读取文件路径[UIImage imageWithContentsOfFile]解决掉这个问题.

NSImage *image = [[NSImage alloc]initWithContentsOfURL:(NSURL *)];

NSImage *image = [[NSImage alloc]initWithContentsOfFile:(NSString *)];

最后要记得释放掉image。 

（2）利用UIImageView实现幻灯片效果

利用UIImageView和UISider来制作幻灯片。

ImagesViewController.h

#import <UIKit/UIKit.h>

@interface ImagesViewController : UIViewController

{

         UIImageView *imageView;

         UISlider *slider;

}

@property (nonatomic, retain) IBOutlet UIImageView *imageView;

@property (nonatomic, retain) IBOutlet UISlider *slider;

- (IBAction)sliderAction:(id)sender;

@end

ImagesViewController.m

#import "ImagesViewController.h"
#import "Constants.h"

#define kMinDuration 0.0
#define kMaxDuration 10.0

@implementation ImagesViewController

@synthesize imageView, slider;

- (void)dealloc
{
    [imageView release];
    [slider release];

    [super dealloc];
}

- (void)viewDidLoad
{    
    [super viewDidLoad];

    self.title = NSLocalizedString(@"ImagesTitle", @"");
    self.imageView.animationImages = [NSArray arrayWithObjects:
     [UIImage imageNamed:@"scene1.jpg"],
     [UIImage imageNamed:@"scene2.jpg"],
     [UIImage imageNamed:@"scene3.jpg"],
     [UIImage imageNamed:@"scene4.jpg"],
     [UIImage imageNamed:@"scene5.jpg"],nil];
    imageView.animationDuration = 5.0;
    [self.imageView stopAnimating];
        imageView.image = [UIImage imageNamed:@"a.png"];
    [self.imageView setIsAccessibilityElement:YES];
    [self.imageView setAccessibilityLabel:self.title];
    [self.slider setAccessibilityLabel:NSLocalizedString(@"DurationSlider",@"")];
}
- (void)viewDidUnload
{
    [super viewDidUnload];

    self.imageView = nil;
    self.slider = nil;
}
- (IBAction)sliderAction:(id)sender
{
    UISlider* durationSlider = sender;
    self.imageView.animationDuration = [durationSlider value];
    if (!self.imageView.isAnimating)
        [self.imageView startAnimating];
}

#pragma mark -
#pragma mark UIViewController delegate methods

- (void)viewWillDisappear:(BOOL)animated
{    
    [self.imageView stopAnimating];

    self.navigationController.navigationBar.barStyle = UIBarStyleDefault;
    [UIApplication sharedApplication].statusBarStyle = UIStatusBarStyleDefault;
}

- (void)viewWillAppear:(BOOL)animated
{    
    [self.imageView startAnimating];
    self.navigationController.navigationBar.barStyle = UIBarStyleBlackOpaque;

    [UIApplication sharedApplication].statusBarStyle = UIStatusBarStyleBlackOpaque;
}

@end

首先通过加载多张图片进入imageView的animationImages里面。再设置动画的时间间隔animationDuration，并设置UISider控制幻灯片播放的速度，让图片像幻灯片那么播放。

2.UIWebView的讲解

(1)初始化

在.h文件中声明UIWebView。

@interface WebViewController : UIViewController {

IBOutlet UIWebView *webView;
}

@property (nonatomic, retain) UIWebView *webView;

@end

在.m文件中初始化UIWebView并载入要读取的URL，如下：

- (void)viewDidLoad {

NSString *urlAddress = @”http://www.google.com”;

//Create a URL object.
NSURL *url = [NSURL URLWithString:urlAddress];

//URL Requst Object
NSURLRequest *requestObj = [NSURLRequest requestWithURL:url];

//Load the request in the UIWebView.
[webView loadRequest:requestObj];
}

并在你的delegate里面载入跟IB一起的XIB文件，如下：

- (void)applicationDidFinishLaunching:(UIApplication *)application {

self.wvTutorial = [[WebViewController alloc] initWithNibName:@”WebView” bundle:[NSBundle mainBundle]];

[window addSubview:[wvTutorial view]];

// Override point for customization after app launch
[window makeKeyAndVisible];
}

今天就讲UIImageView和UIWebView的利用，这两个都是比较有用的，在以后的开发中布局会经常用到，最后，谢谢大家支持。欢迎大家拍砖。