Added nullability annotations and nil defaults.

Pod/Classes/MBCircularProgressBarLayer.h

@@ -17,121 +17,121 @@
 /**
  * Set a partial angle for the progress bar	[0,100]
  */
-@property (nonatomic,assign) CGFloat  progressAngle;
+@property (nonatomic,assign)            CGFloat     progressAngle;
 
 /**
  * Progress bar rotation (Clockewise)	[0,100]
  */
-@property (nonatomic,assign) CGFloat  progressRotationAngle;
+@property (nonatomic,assign)            CGFloat     progressRotationAngle;
 
 /**
  * The value of the progress bar
  */
-@property (nonatomic,assign) CGFloat  value;
+@property (nonatomic,assign)            CGFloat     value;
 
 /**
  * The maximum possible value, used to calculate the progress (value/maxValue)	[0,∞)
  */
-@property (nonatomic,assign) CGFloat  maxValue;
+@property (nonatomic,assign)            CGFloat     maxValue;
 
 /**
  * Animation duration in seconds
  */
-@property (nonatomic,assign) NSTimeInterval  animationDuration;
+@property (nonatomic,assign)            NSTimeInterval  animationDuration;
 
 /**
  * Defines if the progress should animate on value change
  */
-@property (nonatomic,assign) BOOL  animated;
+@property (nonatomic,assign)            BOOL        animated;
 
 /**
  * The font size of the value text	[0,∞)
  */
-@property (nonatomic,assign) CGFloat  valueFontSize;
+@property (nonatomic,assign)            CGFloat     valueFontSize;
 
 /**
  * The name of the font of the unit string
  */
-@property (nonatomic,assign) CGFloat  unitFontSize;
+@property (nonatomic,assign)            CGFloat     unitFontSize;
 
 /**
  * The string that represents the units, usually %
  */
-@property (nonatomic,copy)   NSString *unitString;
+@property (nonatomic,copy,nullable)     NSString    *unitString;
 
 /**
  * The color of the value and unit text
  */
-@property (nonatomic,strong) UIColor  *fontColor;
+@property (nonatomic,strong,nullable)   UIColor     *fontColor;
 
 /**
  * The width of the progress bar (user space units)	[0,∞)
  */
-@property (nonatomic,assign) CGFloat    progressLineWidth;
+@property (nonatomic,assign)            CGFloat     progressLineWidth;
 
 /**
  * The color of the progress bar
  */
-@property (nonatomic,strong) UIColor    *progressColor;
+@property (nonatomic,strong,nullable)   UIColor     *progressColor;
 
 /**
  * The color of the progress bar frame
  */
-@property (nonatomic,strong) UIColor    *progressStrokeColor;
+@property (nonatomic,strong,nullable)   UIColor     *progressStrokeColor;
 
 /**
  * The shape of the progress bar cap	{kCGLineCapButt=0, kCGLineCapRound=1, kCGLineCapSquare=2}
  */
-@property (nonatomic,assign) CGLineCap  progressCapType;
+@property (nonatomic,assign)            CGLineCap   progressCapType;
 
 /**
  * The width of the background bar (user space units)	[0,∞)
  */
-@property (nonatomic,assign) CGFloat    emptyLineWidth;
+@property (nonatomic,assign)            CGFloat     emptyLineWidth;
 
 /**
  * The shape of the background bar cap	{kCGLineCapButt=0, kCGLineCapRound=1, kCGLineCapSquare=2}
  */
-@property (nonatomic,assign) CGLineCap  emptyCapType;
+@property (nonatomic,assign)            CGLineCap   emptyCapType;
 
 /**
  * The color of the background bar
  */
-@property (nonatomic,strong) UIColor    *emptyLineColor;
+@property (nonatomic,strong,nullable)   UIColor     *emptyLineColor;
 
 /*
  * Number of decimal places of the value [0,∞)
  */
-@property (nonatomic,assign)  NSInteger decimalPlaces;
+@property (nonatomic,assign)            NSInteger   decimalPlaces;
 
 /**
  * The value to be displayed in the center
  */
-@property (nonatomic,assign)  CGFloat   valueDecimalFontSize;
+@property (nonatomic,assign)            CGFloat     valueDecimalFontSize;
 
 /**
  * The font size of the unit text	[0,∞)
  */
-@property (nonatomic,copy)    NSString  *unitFontName;
+@property (nonatomic,copy,nullable)     NSString    *unitFontName;
 
 /**
  * The name of the font of the unit string
  */
-@property (nonatomic,copy)    NSString  *valueFontName;
+@property (nonatomic,copy,nullable)     NSString    *valueFontName;
 
 /**
  * Should show unit screen
  */
-@property (nonatomic,assign)  BOOL      showUnitString;
+@property (nonatomic,assign)            BOOL        showUnitString;
 
 /**
  * The offset to apply to the unit / value text
  */
-@property (nonatomic,assign)  CGPoint   textOffset;
+@property (nonatomic,assign)            CGPoint     textOffset;
 
 /**
  * Should show value string
  */
-@property (nonatomic,assign)  BOOL      showValueString;
+@property (nonatomic,assign)            BOOL        showValueString;
 
 @end

Pod/Classes/MBCircularProgressBarLayer.m

@@ -78,8 +78,16 @@ - (void)drawEmptyBar:(CGSize)rectSize context:(CGContextRef)c{
 
 
     CGContextAddPath(c, strokedArc);
-    CGContextSetStrokeColorWithColor(c, self.emptyLineColor.CGColor);
-    CGContextSetFillColorWithColor(c, self.emptyLineColor.CGColor);
+
+    CGColorRef emptyLineColor;
+    if (self.emptyLineColor) {
+        emptyLineColor = self.emptyLineColor.CGColor;
+    } else {
+        emptyLineColor = [UIColor lightGrayColor].CGColor;
+    }
+
+    CGContextSetStrokeColorWithColor(c, emptyLineColor);
+    CGContextSetFillColorWithColor(c, emptyLineColor);
     CGContextDrawPath(c, kCGPathFillStroke);
 
     CGPathRelease(arc);
@@ -109,8 +117,23 @@ - (void)drawProgressBar:(CGSize)rectSize context:(CGContextRef)c{
 
 
     CGContextAddPath(c, strokedArc);
-    CGContextSetFillColorWithColor(c, self.progressColor.CGColor);
-    CGContextSetStrokeColorWithColor(c, self.progressStrokeColor.CGColor);
+
+    CGColorRef progressColor;
+    if (self.progressColor) {
+        progressColor = self.progressColor.CGColor;
+    } else {
+        progressColor = [UIColor orangeColor].CGColor;
+    }
+    CGContextSetFillColorWithColor(c, progressColor);
+
+    CGColorRef progressStrokeColor;
+    if (self.progressStrokeColor) {
+        progressStrokeColor = self.progressStrokeColor.CGColor;
+    } else {
+        progressStrokeColor = [UIColor orangeColor].CGColor;
+    }
+    CGContextSetStrokeColorWithColor(c, progressStrokeColor);
+
     CGContextDrawPath(c, kCGPathFillStroke);
 
     CGPathRelease(arc);
@@ -124,9 +147,21 @@ - (void)drawText:(CGSize)rectSize context:(CGContextRef)c
   NSMutableParagraphStyle* textStyle = NSMutableParagraphStyle.defaultParagraphStyle.mutableCopy;
   textStyle.alignment = NSTextAlignmentLeft;
 
-  CGFloat valueFontSize = self.valueFontSize == -1 ? rectSize.height/5 : self.valueFontSize;
+  CGFloat valueFontSize = self.valueFontSize < 0 ? rectSize.height/5 : self.valueFontSize;
 
-  NSDictionary* valueFontAttributes = @{NSFontAttributeName: [UIFont fontWithName: self.valueFontName size:valueFontSize], NSForegroundColorAttributeName: self.fontColor, NSParagraphStyleAttributeName: textStyle};
+  UIFont* valueFont = [UIFont fontWithName:self.valueFontName size:valueFontSize];
+  if (!valueFont) {
+    valueFont = [UIFont systemFontOfSize:valueFontSize];
+  }
+
+    UIColor* fontColor;
+    if (self.fontColor) {
+        fontColor = self.fontColor;
+    } else {
+        fontColor = [UIColor blackColor];
+    }
+
+  NSDictionary* valueFontAttributes = @{NSFontAttributeName: valueFont, NSForegroundColorAttributeName: fontColor, NSParagraphStyleAttributeName: textStyle};
 
   NSMutableAttributedString *text = [NSMutableAttributedString new];
 
@@ -140,17 +175,34 @@ - (void)drawText:(CGSize)rectSize context:(CGContextRef)c
   // set the decimal font size
   NSUInteger decimalLocation = [text.string rangeOfString:@"."].location;
   if (decimalLocation != NSNotFound){
-    NSDictionary* valueDecimalFontAttributes = @{NSFontAttributeName: [UIFont fontWithName: self.valueFontName size:self.valueDecimalFontSize == -1 ? valueFontSize : self.valueDecimalFontSize], NSForegroundColorAttributeName: self.fontColor, NSParagraphStyleAttributeName: textStyle};
+    UIFont* valueDecimalFont = [UIFont fontWithName:self.valueFontName size:self.valueDecimalFontSize < 0 ? valueFontSize : self.valueDecimalFontSize];
+    if (!valueDecimalFont) {
+      valueDecimalFont = [UIFont systemFontOfSize:valueFontSize];
+    }
+
+    NSDictionary* valueDecimalFontAttributes = @{NSFontAttributeName: valueDecimalFont, NSForegroundColorAttributeName: fontColor, NSParagraphStyleAttributeName: textStyle};
     NSRange decimalRange = NSMakeRange(decimalLocation, text.length - decimalLocation);
     [text setAttributes:valueDecimalFontAttributes range:decimalRange];
   }
 
   // ad the unit only if specified
   if (self.showUnitString) {
-    NSDictionary* unitFontAttributes = @{NSFontAttributeName: [UIFont fontWithName: self.unitFontName size:self.unitFontSize == -1 ? rectSize.height/7 : self.unitFontSize], NSForegroundColorAttributeName: self.fontColor, NSParagraphStyleAttributeName: textStyle};
-
+    UIFont* unitFont = [UIFont fontWithName:self.unitFontName size:self.unitFontSize < 0 ? rectSize.height/7 : self.unitFontSize];
+    if (!unitFont) {
+      unitFont = [UIFont systemFontOfSize:valueFontSize];
+    }
+
+    NSDictionary* unitFontAttributes = @{NSFontAttributeName: unitFont, NSForegroundColorAttributeName: fontColor, NSParagraphStyleAttributeName: textStyle};
+
+    NSString* unitString;
+    if (self.unitString) {
+      unitString = [NSString stringWithFormat:@"%@", self.unitString];
+    } else {
+      unitString = @"%";
+    }
+
     NSAttributedString* unit =
-    [[NSAttributedString alloc] initWithString:[NSString stringWithFormat:@"%@", self.unitString] attributes:unitFontAttributes];
+    [[NSAttributedString alloc] initWithString:unitString attributes:unitFontAttributes];
     [text appendAttributedString:unit];
   }
 

Pod/Classes/MBCircularProgressBarView.h

@@ -18,112 +18,112 @@ IB_DESIGNABLE
 /**
  * Should show value string 
  */
-@property (nonatomic,assign) IBInspectable BOOL      showValueString;
+@property (nonatomic,assign)            IBInspectable BOOL      showValueString;
 
 /**
  * The value of the progress bar  
  */
-@property (nonatomic,assign) IBInspectable CGFloat   value;
+@property (nonatomic,assign)            IBInspectable CGFloat   value;
 
 /** 
- * The maximum possible value, used to calculate the progress (value/maxValue)	[0,∞) 
+ * The maximum possible value, used to calculate the progress (value/maxValue) [0,∞)
  */
-@property (nonatomic,assign) IBInspectable CGFloat   maxValue;
+@property (nonatomic,assign)            IBInspectable CGFloat   maxValue;
 
 /* 
  * Number of decimal places of the value [0,∞) 
  */
-@property (nonatomic,assign) IBInspectable NSInteger decimalPlaces;
+@property (nonatomic,assign)            IBInspectable NSInteger decimalPlaces;
 
 /** 
  * The name of the font of the value string
  */
-@property (nonatomic,copy)   IBInspectable NSString  *valueFontName;
+@property (nonatomic,copy,nullable)     IBInspectable NSString  *valueFontName;
 
 /**
  * The font size of the value text	[0,∞) 
  */
-@property (nonatomic,assign) IBInspectable CGFloat   valueFontSize;
+@property (nonatomic,assign)            IBInspectable CGFloat   valueFontSize;
 
 /** 
  * The value to be displayed in the center 
  */
-@property (nonatomic,assign) IBInspectable CGFloat   valueDecimalFontSize;
+@property (nonatomic,assign)            IBInspectable CGFloat   valueDecimalFontSize;
 
 /**
  * Should show unit screen 
  */
-@property (nonatomic,assign) IBInspectable BOOL      showUnitString;
+@property (nonatomic,assign)            IBInspectable BOOL      showUnitString;
 
 /**
  * The name of the font of the unit string 
  */
-@property (nonatomic,copy)   IBInspectable NSString  *unitFontName;
+@property (nonatomic,copy,nullable)     IBInspectable NSString  *unitFontName;
 
 /**
- * The font size of the unit text	[0,∞) 
+ * The font size of the unit text [0,∞) 
  */
-@property (nonatomic,assign) IBInspectable CGFloat   unitFontSize;
+@property (nonatomic,assign)            IBInspectable CGFloat   unitFontSize;
 
 /** 
  * The string that represents the units, usually % 
  */
-@property (nonatomic,copy)   IBInspectable NSString  *unitString;
+@property (nonatomic,copy,nullable)     IBInspectable NSString  *unitString;
 
 /** 
  * The color of the value and unit text 
  */
-@property (nonatomic,strong) IBInspectable UIColor   *fontColor;
+@property (nonatomic,strong,nullable)   IBInspectable UIColor   *fontColor;
 
 /**
  * Progress bar rotation (Clockewise)	[0,100] 
  */
-@property (nonatomic,assign) IBInspectable CGFloat   progressRotationAngle;
+@property (nonatomic,assign)            IBInspectable CGFloat   progressRotationAngle;
 
 /** 
  * Set a partial angle for the progress bar	[0,100] 
  */
-@property (nonatomic,assign) IBInspectable CGFloat   progressAngle;
+@property (nonatomic,assign)            IBInspectable CGFloat   progressAngle;
 
 /** 
  * The width of the progress bar (user space units)	[0,∞)
  */
-@property (nonatomic,assign) IBInspectable CGFloat   progressLineWidth;
+@property (nonatomic,assign)            IBInspectable CGFloat   progressLineWidth;
 
 /** 
  * The color of the progress bar 
  */
-@property (nonatomic,strong) IBInspectable UIColor   *progressColor;
+@property (nonatomic,strong,nullable)   IBInspectable UIColor   *progressColor;
 
 /**
  * The color of the progress bar frame 
  */
-@property (nonatomic,strong) IBInspectable UIColor   *progressStrokeColor;
+@property (nonatomic,strong,nullable)   IBInspectable UIColor   *progressStrokeColor;
 
 /**
- * The shape of the progress bar cap	{kCGLineCapButt=0, kCGLineCapRound=1, kCGLineCapSquare=2} 
+ * The shape of the progress bar cap {kCGLineCapButt=0, kCGLineCapRound=1, kCGLineCapSquare=2}
  */
-@property (nonatomic,assign) IBInspectable NSInteger progressCapType;
+@property (nonatomic,assign)            IBInspectable NSInteger progressCapType;
 
 /**
  * The width of the background bar (user space units)	[0,∞) 
  */
-@property (nonatomic,assign) IBInspectable CGFloat   emptyLineWidth;
+@property (nonatomic,assign)            IBInspectable CGFloat   emptyLineWidth;
 
 /**
  * The color of the background bar 
  */
-@property (nonatomic,strong) IBInspectable UIColor   *emptyLineColor;
+@property (nonatomic,strong,nullable)   IBInspectable UIColor   *emptyLineColor;
 
 /**
- * The shape of the background bar cap	{kCGLineCapButt=0, kCGLineCapRound=1, kCGLineCapSquare=2} 
+ * The shape of the background bar cap {kCGLineCapButt=0, kCGLineCapRound=1, kCGLineCapSquare=2}
  */
-@property (nonatomic,assign) IBInspectable NSInteger emptyCapType;
+@property (nonatomic,assign)            IBInspectable NSInteger emptyCapType;
 
 /**
  * The offset to apply to the unit / value text
  */
-@property (nonatomic,assign) IBInspectable CGPoint textOffset;
+@property (nonatomic,assign)            IBInspectable CGPoint   textOffset;
 
 /** 
  * Set the value of the progress bar with animation