Im was looking the REMenu lib code, and see a vars being declared as wiht ({ ... }); .. looks something like 'closure' to lazy evaluated code.. I don't know.. Someone can explain me?
self.menuWrapperView = ({
UIView *view = [[UIView alloc] init];
view.autoresizingMask = UIViewAutoresizingFlexibleWidth;
if (!self.liveBlur || !REUIKitIsFlatMode()) {
view.layer.shadowColor = self.shadowColor.CGColor;
view.layer.shadowOffset = self.shadowOffset;
view.layer.shadowOpacity = self.shadowOpacity;
view.layer.shadowRadius = self.shadowRadius;
view.layer.shouldRasterize = YES;
view.layer.rasterizationScale = [UIScreen mainScreen].scale;
}
view;
});
self.toolbar = ({
UIToolbar *toolbar = [[UIToolbar alloc] init];
toolbar.barStyle = self.liveBlurBackgroundStyle;
if ([toolbar respondsToSelector:@selector(setBarTintColor:)])
[toolbar performSelector:@selector(setBarTintColor:) withObject:self.liveBlurTintColor];
toolbar.autoresizingMask = UIViewAutoresizingFlexibleWidth;
toolbar;
});
Variable Declaration in Objective-C You will use extern keyword to declare a variable at any place. Though you can declare a variable multiple times in your Objective-C program but it can be defined only once in a file, a function or a block of code.
Declaring an int variable In Swift, the “var” keyword is used to declare a variable and you don't have to specify the type if it can be inferred from what you're assigning it. Also notice in Swift, we're using the String class as opposed to NSString.
A variable declaration provides assurance to the compiler that there exists a variable with the given type and name so that the compiler can proceed for further compilation without requiring the complete detail about the variable.
This is a GNU (non-standard) C language extension called a “statement expression”. The syntax is supported by gcc, clang, and several other compilers.
Basically, it lets you treat an arbitrary block as a single expression, whose value is the value of the last statement in the block.
This extension is mostly useful is macro definitions. In my opinion, the code you quoted in your question (from the showFromRect:inView:
method in REMenu.m
) would be better if it did not use statement expressions. Instead, the code in those statement expressions should be factored out into separate methods. For example:
self.menuWrapperView = [self newMenuWrapperView];
self.toolbar = [self newToolbar];
...
- (UIView *)newMenuWrapperView {
UIView *view = [[UIView alloc] init];
view.autoresizingMask = UIViewAutoresizingFlexibleWidth;
if (!self.liveBlur || !REUIKitIsFlatMode()) {
view.layer.shadowColor = self.shadowColor.CGColor;
view.layer.shadowOffset = self.shadowOffset;
view.layer.shadowOpacity = self.shadowOpacity;
view.layer.shadowRadius = self.shadowRadius;
view.layer.shouldRasterize = YES;
view.layer.rasterizationScale = [UIScreen mainScreen].scale;
}
return view;
}
- (UIToolbar *)newToolbar {
UIToolbar *toolbar = [[UIToolbar alloc] init];
toolbar.barStyle = self.liveBlurBackgroundStyle;
if ([toolbar respondsToSelector:@selector(setBarTintColor:)])
[toolbar performSelector:@selector(setBarTintColor:) withObject:self.liveBlurTintColor];
toolbar.autoresizingMask = UIViewAutoresizingFlexibleWidth;
return toolbar;
}
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