Add the ability to modify the default format block

Author: joeljfischer

SuperLogger/SLLoggerController.h

@@ -37,7 +37,7 @@ NS_ASSUME_NONNULL_BEGIN
 /**
  *  The default format block that will be used if a logger's format block is nil
  */
-@property (copy, nonatomic, readonly) SLLogFormatBlock defaultFormatBlock;
+@property (copy, nonatomic) SLLogFormatBlock defaultFormatBlock;
 
 /**
  *  Whether or not non-error logs will be dispatched asynchronously.

SuperLogger/SLLoggerController.m

@@ -25,6 +25,8 @@ @interface SLLoggerController ()
 
 @implementation SLLoggerController
 
+@synthesize defaultFormatBlock = _defaultFormatBlock;
+
 #pragma mark - Lifecycle
 
 + (SLLoggerController *)sharedController {
@@ -50,6 +52,7 @@ - (instancetype)init {
     _async = YES;
     _errorAsync = NO;
     _globalLogLevel = SLLogLevelDebug;
+    _defaultFormatBlock = nil;
 
     return self;
 }
@@ -127,11 +130,21 @@ + (SLLogLevel)logLevelForFile:(NSString *)file {
 #pragma mark - Getters / Setters
 
 - (SLLogFormatBlock)defaultFormatBlock {
-    return ^NSString * (SLLog *log) {
-        NSString *callerClass = log.fileName;
-        NSString *callerFunction = log.functionName;
-        return [NSString stringWithFormat:@"(%@:%@)[%@ %@] %@", log.queueLabel, log.timestamp, callerClass, callerFunction, log.message];
-    };
+    if (_defaultFormatBlock != nil) {
+        return _defaultFormatBlock;
+    } else {
+        return [^NSString * (SLLog *log) {
+            NSString *callerClass = log.fileName;
+            NSString *callerFunction = log.functionName;
+            return [NSString stringWithFormat:@"(%@:%@)[%@ %@] %@", log.queueLabel, log.timestamp, callerClass, callerFunction, log.message];
+        } copy];
+    }
+}
+
+- (void)setDefaultFormatBlock:(SLLogFormatBlock)defaultFormatBlock {
+    dispatch_async([self.class globalLogQueue], ^{
+        _defaultFormatBlock = defaultFormatBlock;
+    });
 }