A nice little customizable view for a progress bar, with optional animation properties

ABProgressBar.h

//
//  ABProgressBar.h
//  Adam L Barrett
//
//  Created by Adam L Barrett on 2013-12-10.
//  Copyright (c) 2013 Adam L Barrett. All rights reserved.
//

#import <UIKit/UIKit.h>
#import <QuartzCore/QuartzCore.h>

@interface GBProgressBar : UIView

@property (nonatomic, assign) double progress;
@property (nonatomic, strong) UIColor *color;

@property (nonatomic, strong) NSString *statusText;
@property (nonatomic, strong) UIColor *textColor;
@property (nonatomic, strong) NSNumber *fontSize;
@property (nonatomic, assign) CGPoint textOffset;
@property (nonatomic, assign) UIEdgeInsets contentInsets;

@property (nonatomic, assign, getter = isAnimated) BOOL animated;
@property (nonatomic, assign) NSTimeInterval animationDuration; // default 1.0
// This will slide up from Zero on appearance of the progress bar
@property (nonatomic, assign) BOOL animateFromZero;
// Animation easing effect
@property (nonatomic, strong) CAMediaTimingFunction *timingFunction;

@end

ABProgressBar.m

//
//  ABProgressBar.m
//  Adam L Barrett
//
//  Created by Adam L Barrett on 2013-12-10.
//  Copyright (c) 2013 Adam L Barrett. All rights reserved.
//

#import "GBProgressBar.h"

@interface GBProgressBar()

@property (nonatomic, strong) UILabel *statusTextLabel;
@property (nonatomic, strong) CALayer *progressLayer;

@end

@implementation GBProgressBar
@synthesize textColor  = _textColor;
@synthesize fontSize   = _fontSize;
@synthesize statusText = _statusText;

#pragma mark - Property Accessors
- (void)setProgress:(double)progress
{
    _progress = progress;
    [self updateStatusText];
    
    if (self.animated) {
        [self animateProgressLayerToProgress:_progress];
    }
    else {
        [self setProgressLayerToProgress:_progress];
    }
}


- (void)setColor:(UIColor *)color
{
    if (![_color isEqual:color]) {
        _color = color;
        self.progressLayer.backgroundColor = _color.CGColor;
        [self setNeedsDisplay];
    }
}


- (UILabel *)statusTextLabel
{
    if (!_statusTextLabel) {
        _statusTextLabel = [[UILabel alloc] init];
        _statusTextLabel.contentMode = UIViewContentModeRedraw;
        _statusTextLabel.backgroundColor = [UIColor clearColor];
        _statusTextLabel.textColor = self.textColor;
        _statusTextLabel.numberOfLines = 1;
        _statusTextLabel.adjustsFontSizeToFitWidth = YES;
        if ([_statusText respondsToSelector:@selector(setMinimumScaleFactor:)]) {
            _statusTextLabel.minimumScaleFactor = 0.2;
        } else {
            _statusTextLabel.minimumFontSize = 8.0;
        }
        _statusTextLabel.font = [UIFont fontWithName:@"Helvetica" size:[self.fontSize floatValue]];
        _statusTextLabel.textAlignment = NSTextAlignmentCenter;
        [self addSubview:self.statusTextLabel];
    }
    return _statusTextLabel;
}


- (UIColor *)textColor
{
    if (!_textColor) {
        _textColor = [UIColor whiteColor];
    }
    return _textColor;
}


- (void)setTextColor:(UIColor *)textColor
{
    if (![_textColor isEqual:textColor]) {
        _textColor = textColor;
        self.statusTextLabel.textColor = _textColor;
    }
}


- (NSString *)statusText
{
    if (!_statusText) {
        return @"%d%%";
    }
    return _statusText;
}


- (void)setStatusText:(NSString *)statusText
{
    if (![_statusText isEqualToString:statusText]) {
        _statusText = statusText;
        [self updateStatusText];
        [self setNeedsDisplay];
    }
}


- (NSNumber *)fontSize
{
    if (!_fontSize) {
        return @20;
    }
    return _fontSize;
}


- (void)setFontSize:(NSNumber *)fontSize
{
    if (![_fontSize isEqualToNumber:fontSize]) {
        _fontSize = fontSize;
        self.statusTextLabel.font = [UIFont fontWithName:@"Helvetica" size:[_fontSize floatValue]];
    }
}


- (CALayer *)progressLayer
{
    if (!_progressLayer) {
        _progressLayer = [CALayer layer];
        _progressLayer.anchorPoint = CGPointZero;
        _progressLayer.backgroundColor = self.color.CGColor;
        
        CGRect b = _progressLayer.bounds;
        b.size.height = self.layer.bounds.size.height;
        b.size.width = 0;
        _progressLayer.bounds = b;
        
        [self.layer insertSublayer:_progressLayer atIndex:0];
    }
    return _progressLayer;
}


#pragma mark - Init
- (void)_init
{
    self.clipsToBounds = YES;
    self.contentInsets = UIEdgeInsetsMake(5, 20, 5, 20);
    self.progress = 0;
    self.animationDuration = 1.0;
}


- (id)init
{
    self = [super init];
    if (self) {
        [self _init];
    }
    return self;
}


- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        [self _init];
    }
    return self;
}


- (id)initWithCoder:(NSCoder *)aDecoder
{
    self = [super initWithCoder:aDecoder];
    if (self) {
        [self _init];
    }
    return self;
}

#pragma mark - Updating Text Label
- (void)updateStatusText
{
    self.statusTextLabel.text = [NSString stringWithFormat:self.statusText, (int)(self.progress * 100)];
}

#pragma mark - Layout
- (void)layoutSubviews
{
    [super layoutSubviews];
    CGRect b = self.bounds;
    
    // Status Text Label
    CGRect stlf = CGRectMake(0, 0, b.size.width, b.size.height);
    stlf = UIEdgeInsetsInsetRect(stlf, self.contentInsets);
    self.statusTextLabel.frame = stlf;
    self.statusTextLabel.center = CGPointMake(CGRectGetMidX(b)+self.textOffset.x, CGRectGetMidY(b)+self.textOffset.y);
}


- (void)animateProgressLayerToProgress:(double)progress
{
    if (self.animateFromZero) {
        [self performBlock:^(id sender) {
            [self setProgressLayerToProgress:progress];
        } afterDelay:0];
    }
    else {
        [self setProgressLayerToProgress:progress];
    }
}

- (void)setProgressLayerToProgress:(double)progress
{
    [CATransaction begin];
    [CATransaction setAnimationDuration: ([self isAnimated] ? self.animationDuration : 0.0)];
    if (self.timingFunction) {
        [CATransaction setAnimationTimingFunction:self.timingFunction];
    }
    if ( ![self isAnimated] ) {
        [CATransaction setDisableActions:YES];
    }
    
    // Transaction
    CGRect b = self.progressLayer.bounds;
    b.size.width = self.bounds.size.width * _progress;
    self.progressLayer.bounds = b;
    
    [CATransaction commit];
}

@end