iOS自定义LoadingView

应用开发的时候，加载数据的时候需要加载页面，如果没用，那么就缺少人性化设计了。系统自带的是UIActivityIndicatorView，但它缺少文字说明，要加上文字说明的loading view只有自子封装。代码如下：

LoadingView.h

#import <UIKit/UIKit.h>

@interface LoadingView : UIView
{

}

+ (id)loadingViewInView:(UIView *)aSuperview;
- (void)removeView;

@end

LoadingView.m

#import "LoadingView.h"
#import <QuartzCore/QuartzCore.h>

//
// NewPathWithRoundRect
//
// Creates a CGPathRect with a round rect of the given radius.
//
CGPathRef NewPathWithRoundRect(CGRect rect, CGFloat cornerRadius)
{
	//
	// Create the boundary path
	//
	CGMutablePathRef path = CGPathCreateMutable();
	CGPathMoveToPoint(path, NULL,
		rect.origin.x,
		rect.origin.y + rect.size.height - cornerRadius);

	// Top left corner
	CGPathAddArcToPoint(path, NULL,
		rect.origin.x,
		rect.origin.y,
		rect.origin.x + rect.size.width,
		rect.origin.y,
		cornerRadius);

	// Top right corner
	CGPathAddArcToPoint(path, NULL,
		rect.origin.x + rect.size.width,
		rect.origin.y,
		rect.origin.x + rect.size.width,
		rect.origin.y + rect.size.height,
		cornerRadius);

	// Bottom right corner
	CGPathAddArcToPoint(path, NULL,
		rect.origin.x + rect.size.width,
		rect.origin.y + rect.size.height,
		rect.origin.x,
		rect.origin.y + rect.size.height,
		cornerRadius);

	// Bottom left corner
	CGPathAddArcToPoint(path, NULL,
		rect.origin.x,
		rect.origin.y + rect.size.height,
		rect.origin.x,
		rect.origin.y,
		cornerRadius);

	// Close the path at the rounded rect
	CGPathCloseSubpath(path);
	
	return path;
}

@implementation LoadingView

//
// loadingViewInView:
//
// Constructor for this view. Creates and adds a loading view for covering the
// provided aSuperview.
//
// Parameters:
//    aSuperview - the superview that will be covered by the loading view
//
// returns the constructed view, already added as a subview of the aSuperview
//	(and hence retained by the superview)
//
+ (id)loadingViewInView:(UIView *)aSuperview
{
	LoadingView *loadingView =
		[[[LoadingView alloc] initWithFrame:[aSuperview bounds]] autorelease];
	if (!loadingView)
	{
		return nil;
	}
	
	loadingView.opaque = NO;
	loadingView.autoresizingMask =
		UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
	[aSuperview addSubview:loadingView];

	const CGFloat DEFAULT_LABEL_WIDTH = 280.0;
	const CGFloat DEFAULT_LABEL_HEIGHT = 50.0;
	CGRect labelFrame = CGRectMake(0, 0, DEFAULT_LABEL_WIDTH, DEFAULT_LABEL_HEIGHT);
	UILabel *loadingLabel =
		[[[UILabel alloc]
			initWithFrame:labelFrame]
		autorelease];
	loadingLabel.text = NSLocalizedString(@"Loading...", nil);
	loadingLabel.textColor = [UIColor whiteColor];
	loadingLabel.backgroundColor = [UIColor clearColor];
	loadingLabel.textAlignment = UITextAlignmentCenter;
	loadingLabel.font = [UIFont boldSystemFontOfSize:[UIFont labelFontSize]];
	loadingLabel.autoresizingMask =
		UIViewAutoresizingFlexibleLeftMargin |
		UIViewAutoresizingFlexibleRightMargin |
		UIViewAutoresizingFlexibleTopMargin |
		UIViewAutoresizingFlexibleBottomMargin;
	
	[loadingView addSubview:loadingLabel];
	UIActivityIndicatorView *activityIndicatorView =
		[[[UIActivityIndicatorView alloc]
			initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhiteLarge]
		autorelease];
	[loadingView addSubview:activityIndicatorView];
	activityIndicatorView.autoresizingMask =
		UIViewAutoresizingFlexibleLeftMargin |
		UIViewAutoresizingFlexibleRightMargin |
		UIViewAutoresizingFlexibleTopMargin |
		UIViewAutoresizingFlexibleBottomMargin;
	[activityIndicatorView startAnimating];
	
	CGFloat totalHeight =
		loadingLabel.frame.size.height +
		activityIndicatorView.frame.size.height;
	labelFrame.origin.x = floor(0.5 * (loadingView.frame.size.width - DEFAULT_LABEL_WIDTH));
	labelFrame.origin.y = floor(0.5 * (loadingView.frame.size.height - totalHeight));
	loadingLabel.frame = labelFrame;
	
	CGRect activityIndicatorRect = activityIndicatorView.frame;
	activityIndicatorRect.origin.x =
		0.5 * (loadingView.frame.size.width - activityIndicatorRect.size.width);
	activityIndicatorRect.origin.y =
		loadingLabel.frame.origin.y + loadingLabel.frame.size.height;
	activityIndicatorView.frame = activityIndicatorRect;
	
	// Set up the fade-in animation
	CATransition *animation = [CATransition animation];
	[animation setType:kCATransitionFade];
	[[aSuperview layer] addAnimation:animation forKey:@"layerAnimation"];
	
	return loadingView;
}

//
// removeView
//
// Animates the view out from the superview. As the view is removed from the
// superview, it will be released.
//
- (void)removeView
{
	UIView *aSuperview = [self superview];
	[super removeFromSuperview];

	// Set up the animation
	CATransition *animation = [CATransition animation];
	[animation setType:kCATransitionFade];
	
	[[aSuperview layer] addAnimation:animation forKey:@"layerAnimation"];
}

//
// drawRect:
//
// Draw the view.
//
- (void)drawRect:(CGRect)rect
{
	rect.size.height -= 1;
	rect.size.width -= 1;
	
	const CGFloat RECT_PADDING = 8.0;
	rect = CGRectInset(rect, RECT_PADDING, RECT_PADDING);
	
	const CGFloat ROUND_RECT_CORNER_RADIUS = 5.0;
	CGPathRef roundRectPath = NewPathWithRoundRect(rect, ROUND_RECT_CORNER_RADIUS);
	
	CGContextRef context = UIGraphicsGetCurrentContext();

	const CGFloat BACKGROUND_OPACITY = 0.85;
	CGContextSetRGBFillColor(context, 0, 0, 0, BACKGROUND_OPACITY);
	CGContextAddPath(context, roundRectPath);
	CGContextFillPath(context);

	const CGFloat STROKE_OPACITY = 0.25;
	CGContextSetRGBStrokeColor(context, 1, 1, 1, STROKE_OPACITY);
	CGContextAddPath(context, roundRectPath);
	CGContextStrokePath(context);
	
	CGPathRelease(roundRectPath);
}

//
// dealloc
//
// Release instance memory.
//
- (void)dealloc
{
    [super dealloc];
}

@end

记得要加入ＱuartzCore.framework 到工程。

用法就更简单了，加入的时候只需调用：

LoadingView *loadingView = [LoadingView loadingViewInView:[self.view.window.subviews objectAtIndex:0]];

删除的时候只需调用：

[loadingView removeFromSuperview];