UIActivityIndicatorView

目的：控制UIActivityIndicatorView元件

Step1.拉UIActivityIndicatorView及按鈕Start及Stop,如下圖

Step2.ViewController.h
@interface ViewController : UIViewController
{
    IBOutlet id indicator;
}

-(IBAction)start:(id)sender;
-(IBAction)stop:(id)sender;

@end

Step3.關聯

Step4.ViewController.m
@implementation ViewController

-(IBAction)start:(id)sender {
    [indicator startAnimating];
}
-(IBAction)stop:(id)sender {
    [indicator stopAnimating];
}