Enable adjustsFontSizeToFitWith for PNChartLabel

@@ -18,10 +18,12 @@
     if (self) {
         // Initialization code
 
-        [self setFont:[UIFont boldSystemFontOfSize:11.0f]];
+        self.font                      = [UIFont boldSystemFontOfSize:11.0f];
         self.backgroundColor           = [UIColor clearColor];
-        [self setTextAlignment:NSTextAlignmentCenter];
+        self.textAlignment             = NSTextAlignmentCenter;
         self.userInteractionEnabled    = YES;
+        self.minimumScaleFactor        = 0.8;
+        self.adjustsFontSizeToFitWidth = YES;
     }
 
     return self;