自定义等待视图

#import <UIKit/UIKit.h>

@interface AlertView : UIView

@property (strong, nonatomic) UILabel *messageLabel;
@end

#import "AlertView.h"

@interface AlertView()
{
    UIActivityIndicatorView *activityIndicatorView;
}
@end

@implementation AlertView
@synthesize messageLabel;

-(id) init
{
    CGRect viewRect = CGRectMake(0, 0, 120, 120);
    self = [super initWithFrame:viewRect];
    
    if (self) {
        [self initSetup];
        [self initActivityIndicatorView];
        [self initMessage];
    }
    return self;
}

-(void) initSetup
{
    CGRect mainRect = [[UIScreen mainScreen] bounds];
    self.backgroundColor = [UIColor blackColor];
    self.center = CGPointMake(mainRect.size.width / 2, mainRect.size.height / 2);
    self.alpha = 0.6;
    [[self layer] setCornerRadius: 15.0];
}

-(void) initActivityIndicatorView
{
    CGRect frameRect = self.frame;
    activityIndicatorView = [[UIActivityIndicatorView alloc]
                             initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhiteLarge];
    activityIndicatorView.center = CGPointMake(frameRect.size.width / 2, frameRect.size.height / 2 - 10);
    [self addSubview:activityIndicatorView];
    [activityIndicatorView startAnimating];
}

-(void) initMessage
{
    messageLabel = [[UILabel alloc]init];
    messageLabel.frame = CGRectMake(0, 0, self.frame.size.width - 15, 20);
    messageLabel.font = [UIFont fontWithName:@"Arial-Bold" size:15];
    messageLabel.textColor = [UIColor whiteColor];
    messageLabel.center =  CGPointMake(self.frame.size.width / 2, self.frame.size.height -20);
    messageLabel.text = @"Please Wait...";
    [self addSubview:messageLabel];
}

@end

#import "ViewController.h"
#import "AlertView.h"

@interface ViewController ()
{
    AlertView *alertView;
}
@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    alertView = nil;
}

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    if (alertView) {
        [alertView removeFromSuperview];
        alertView = nil;
    }
    else
    {
        alertView = [[AlertView alloc]init];
        [self.view addSubview:alertView];
    }
}