Introduction

A loader is something in a service based app for loading data from the server, it takes time to download heavy data such as audio, images and so on. For a better user experience developers show an activity view until the download completes.

The following is the procedure to create and use it in an application.

Step 1

Open XCode by double-clicking on it.

Step 2

Create a UIView class like the following.

UIView Class

Step 3

Take User Interface View like the following:

user interface view

Step 4

Now here we will write the code in the UIView class Objective-C file.

BActivityIndicator.h

  1. #import < UIKit / UIKit.h >
  3. @interface BActivityIndicator: UIView {
  4. CGAffineTransform rotationTransform;
  5. }@property(weak, nonatomic) IBOutlet UILabel * pleaseWaitLabel;@property(weak, nonatomic) IBOutlet UIImageView * spinningImage;
  7. - (id) initWithView: (UIView * ) view;
  9. + (BActivityIndicator * ) showHUDAddedTo: (UIView * ) view animated: (BOOL) animated;
  11. + (BOOL) hideHUDForView: (UIView * ) view animated: (BOOL) animated;
  13. @end
BActivityIndicator.m
  1. #import "BActivityIndicator.h"
  3. @implementation BActivityIndicator
  5. - (id) initWithFrame: (CGRect) frame {
  6. self = [super initWithFrame: frame];
  7. if (self) {
  8. self = [
  9. [
  10. [NSBundle mainBundle] loadNibNamed: @
  11. "BActivityIndicator"
  12. owner: self
  13. options: nil] lastObject];
  14. self.frame = frame;
  15. [self rotateLayerInfinite];
  17. self.pleaseWaitLabel.font = [UIFont fontWithName: @
  18. "RobotoCondensed-Regular"
  19. size: 14.0f];
  20. }
  21. return self;
  22. }
  24. - (id) initWithView: (UIView * ) view {
  25. // Let's check if the view is nil (this is a common error when using the windw initializer above)
  26. if (!view) {
  27. [NSException raise: @
  28. "MBProgressHUDViewIsNillException"
  29. format: @
  30. "The view used in the MBProgressHUD initializer is nil."];
  31. }
  32. id me = [self initWithFrame: CGRectMake(0, 0, [UIScreen mainScreen].bounds.size.width, [UIScreen mainScreen].bounds.size.height)];
  33. // We need to take care of rotation ourselfs if we're adding the HUD to a window
  34. if ([view isKindOfClass: [UIWindow class]]) {
  35. [self setTransformForCurrentOrientation: NO];
  36. }
  37. [
  38. [NSNotificationCenter defaultCenter] addObserver: self selector: @selector(deviceOrientationDidChange: )
  39. name: UIDeviceOrientationDidChangeNotification object: nil];
  41. return me;
  42. }
  45. - (void) rotateLayerInfinite {
  46. CABasicAnimation * rotation;
  47. rotation = [CABasicAnimation animationWithKeyPath: @
  48. "transform.rotation"];
  49. rotation.fromValue = [NSNumber numberWithFloat: 0];
  50. rotation.toValue = [NSNumber numberWithFloat: (2 * M_PI)];
  51. rotation.duration = 1.5f;
  52. rotation.repeatCount = HUGE_VALF;
  53. [_spinningImage.layer removeAllAnimations];
  54. [_spinningImage.layer addAnimation: rotation forKey: @
  55. "Spin"];
  56. }
  58. #pragma mark - #pragma mark Manual oritentation change
  60. #define RADIANS(degrees)((degrees * (float) M_PI) / 180.0f)
  62. - (void) deviceOrientationDidChange: (NSNotification * ) notification {
  63. if (!self.superview) {
  64. return;
  65. }
  66. if ([self.superview isKindOfClass: [UIWindow class]]) {
  67. [self setTransformForCurrentOrientation: YES];
  68. }
  69. }
  71. - (void) setTransformForCurrentOrientation: (BOOL) animated {
  72. UIInterfaceOrientation orientation = [UIApplication sharedApplication].statusBarOrientation;
  73. NSInteger degrees = 0;
  75. // Stay in sync with the superview
  76. if (self.superview) {
  77. self.bounds = self.superview.bounds;
  78. [self setNeedsDisplay];
  79. }
  81. if (UIInterfaceOrientationIsLandscape(orientation)) {
  82. if (orientation == UIInterfaceOrientationLandscapeLeft) {
  83. degrees = -90;
  84. } else {
  85. degrees = 90;
  86. }
  87. // Window coordinates differ!
  88. self.bounds = CGRectMake(0, 0, self.bounds.size.height, self.bounds.size.width);
  89. } else {
  90. if (orientation == UIInterfaceOrientationPortraitUpsideDown) {
  91. degrees = 180;
  92. } else {
  93. degrees = 0;
  94. }
  95. }
  97. rotationTransform = CGAffineTransformMakeRotation(RADIANS(degrees));
  99. if (animated) {
  100. [UIView beginAnimations: nil context: nil];
  101. }
  102. [self setTransform: rotationTransform];
  103. if (animated) {
  104. [UIView commitAnimations];
  105. }
  106. }
  108. + (BActivityIndicator * ) showHUDAddedTo: (UIView * ) view animated: (BOOL) animated {
  109. BActivityIndicator * hud = [
  110. [BActivityIndicator alloc] initWithView: view];
  111. [view addSubview: hud];
  112. return hud;
  113. }
  115. + (BOOL) hideHUDForView: (UIView * ) view animated: (BOOL) animated {
  116. UIView * viewToRemove = nil;
  117. for (UIView * v in [view subviews]) {
  118. if ([v isKindOfClass: [BActivityIndicator class]]) {
  119. viewToRemove = v;
  120. }
  121. }
  122. if (viewToRemove != nil) {
  123. [viewToRemove removeFromSuperview];
  124. return YES;
  125. } else {
  126. return NO;
  127. }
  128. }
  130. - (void) dealloc {
  131. [_spinningImage.layer removeAnimationForKey: @
  132. "Spin"];
  133. }
  135. @end
ViewController.Xib

ViewController

Step 7

Now here I’ll explain how to call that class within a project.

In your common Utility Class you need to write these functions for calling it:
  1. #pragma mark - Activity Indicator + (void) startActivityIndicatorInView: (UIView * ) aView withMessage: (NSString * ) aMessage {
  2. // MBProgressHUD *_hud = [MBProgressHUD showHUDAddedTo:aView animated:YES];
  3. // _hud.dimBackground = YES;
  4. // _hud.labelText = aMessage;
  6. BActivityIndicator * _hud = [BActivityIndicator showHUDAddedTo: aView animated: YES];
  7. // _hud.pleaseWaitLabel.text = aMessage;
  9. }
  11. + (void) stopActivityIndicatorInView: (UIView * ) aView {
  12. // [MBProgressHUD hideHUDForView:aView animated:YES];
  13. [BActivityIndicator hideHUDForView: aView animated: YES];
  14. }
Output

output