简化UIActivityIndicatorView的创建和使用

头文件：

 

#define activityViewTag 0x98751234

@interface UIView (ActivityView) 

- (void)showActivityViewAtCenter;
- (void)hideActivityViewAtCenter;
- (UIActivityIndicatorView *)createActivityViewAtCenter:(UIActivityIndicatorViewStyle)style;
- (UIActivityIndicatorView *)getActivityViewAtCenter;

@end

 

实现文件：

 

#import "UIView.h"

@implementation UIView (ActivityView)

- (void)showActivityViewAtCenter
{
	UIActivityIndicatorView *activityView = [self getActivityViewAtCenter];
	if (activityView == nil){
		activityView = [self createActivityViewAtCenter:UIActivityIndicatorViewStyleWhite];
	}	
	[activityView startAnimating];
}

- (void)hideActivityViewAtCenter
{
	UIActivityIndicatorView *activityView = [self getActivityViewAtCenter];
	if (activityView != nil){
		[activityView stopAnimating];
	}        
}

- (UIActivityIndicatorView *)createActivityViewAtCenter:(UIActivityIndicatorViewStyle)style
{
	static int size = 30;
	
	UIActivityIndicatorView *activityView = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:style];
	activityView.frame = CGRectMake([UIScreen mainScreen].bounds.size.width / 2 - size / 2, [UIScreen mainScreen].bounds.size.height / 2 - size * 2, size, size);
	activityView.tag = activityViewTag;
	[self addSubview:activityView];
	[activityView release];
	
	return activityView;
}

- (UIActivityIndicatorView *)getActivityViewAtCenter
{
	UIView *view = [self viewWithTag:activityViewTag];
	if (view != nil && [view isKindOfClass:[UIActivityIndicatorView class]]){
		return (UIActivityIndicatorView *)view;
	} else {
		return nil;
	}
}

@end