/* |
File: MetricPickerController.m |
Abstract: Controller to managed a picker view displaying metric weights. |
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Version: 1.5 |
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Copyright (C) 2014 Apple Inc. All Rights Reserved. |
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*/ |
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#import "MetricPickerController.h" |
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@interface MetricPickerController () <UIPickerViewDataSource, UIPickerViewDelegate> |
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@property (nonatomic, strong) IBOutlet UIPickerView *pickerView; |
@property (nonatomic, strong) IBOutlet UILabel *label; |
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- (UIView *)viewForComponent:(NSInteger)component; |
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@end |
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#pragma mark - |
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@implementation MetricPickerController |
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// identifiers and widths for the various components |
#define KG_COMPONENT 0 |
#define KG_COMPONENT_WIDTH 88 |
#define KG0_LABEL_WIDTH 46 |
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#define G0_COMPONENT 3 |
#define G0_COMPONENT_WIDTH 74 |
#define G0_LABEL_WIDTH 44 |
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#define G_COMPONENT_WIDTH 50 |
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// Identifies for component views |
#define VIEW_TAG 41 |
#define SUB_LABEL_TAG 42 |
#define LABEL_TAG 43 |
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- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView { |
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return 4; |
} |
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- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component { |
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// Number of rows depends on the currently-selected unit and the component. |
if (component == KG_COMPONENT) { |
return 20; |
} |
return 10; |
} |
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- (UIView *)labelCellWidth:(CGFloat)width rightOffset:(CGFloat)offset { |
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// Create a new view that contains a label offset from the right. |
CGRect frame = CGRectMake(0.0, 0.0, width, 32.0); |
UIView *view = [[UIView alloc] initWithFrame:frame]; |
view.tag = VIEW_TAG; |
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frame.size.width = width - offset; |
UILabel *subLabel = [[UILabel alloc] initWithFrame:frame]; |
subLabel.textAlignment = NSTextAlignmentRight; |
subLabel.backgroundColor = [UIColor clearColor]; |
subLabel.font = [UIFont systemFontOfSize:24.0]; |
subLabel.userInteractionEnabled = NO; |
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subLabel.tag = SUB_LABEL_TAG; |
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[view addSubview:subLabel]; |
return view; |
} |
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- (UIView *)viewForComponent:(NSInteger)component { |
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/* |
Return a view appropriate for the specified picker view and component. |
If it's the picker view, or if it's the kg or g component of the metric view, create a UIView that contains a label. The label can then be offset in the containing view so that its text does not overlap the unit symbol. |
For the remaining components, simple create a label to contain the text. |
Give all the views tags so they can be idntified easily. |
*/ |
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if (component == KG_COMPONENT) { |
return [self labelCellWidth:KG_COMPONENT_WIDTH rightOffset:KG0_LABEL_WIDTH]; |
} |
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if (component == G0_COMPONENT) { |
return [self labelCellWidth:G0_COMPONENT_WIDTH rightOffset:G0_LABEL_WIDTH]; |
} |
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CGRect frame = CGRectMake(0.0, 0.0, 36.0, 32.0); |
UILabel *aLabel = [[UILabel alloc] initWithFrame:frame]; |
aLabel.textAlignment = NSTextAlignmentCenter; |
aLabel.backgroundColor = [UIColor clearColor]; |
aLabel.font = [UIFont systemFontOfSize:24.0]; |
aLabel.userInteractionEnabled = NO; |
aLabel.tag = LABEL_TAG; |
return aLabel; |
} |
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- (UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(UIView *)view { |
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UIView *returnView = nil; |
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// Reuse the label if possible, otherwise create and configure a new one. |
if ((view.tag == VIEW_TAG) || (view.tag == LABEL_TAG)) { |
returnView = view; |
} |
else { |
returnView = [self viewForComponent:component]; |
} |
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// The text shown in the component is just the number of the component. |
NSString *text = [NSString stringWithFormat:@"%d", row]; |
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// Where to set the text in depends on what sort of view it is. |
UILabel *theLabel = nil; |
if (returnView.tag == VIEW_TAG) { |
theLabel = (UILabel *)[returnView viewWithTag:SUB_LABEL_TAG]; |
} |
else { |
theLabel = (UILabel *)returnView; |
} |
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theLabel.text = text; |
return returnView; |
} |
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- (CGFloat)pickerView:(UIPickerView *)pickerView widthForComponent:(NSInteger)component { |
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// The width of the component depends on the currently-selected unit and the component. |
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if (component == KG_COMPONENT) { |
return KG_COMPONENT_WIDTH; |
} |
if (component == G0_COMPONENT) { |
return G0_COMPONENT_WIDTH; |
} |
return G_COMPONENT_WIDTH; |
} |
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- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component { |
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// If the user chooses a new row, update the label accordingly. |
[self updateLabel]; |
} |
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- (void)updateLabel { |
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/* |
If the user has entered metric units, find the number of grams and convert that to pounds and ounces. |
Don't display 0 lbs; round 15.95 ounces up to 1 lb, and use NSDecimalNumberHandler to round ounces for a more attractive display. |
*/ |
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static NSDecimalNumberHandler* roundingBehavior = nil; |
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if (roundingBehavior == nil) { |
roundingBehavior = |
[[NSDecimalNumberHandler alloc] initWithRoundingMode:NSRoundPlain |
scale:1 |
raiseOnExactness:NO |
raiseOnOverflow:NO |
raiseOnUnderflow:NO |
raiseOnDivideByZero:NO]; |
} |
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NSInteger grams = 0; |
grams += [self.pickerView selectedRowInComponent:3]; |
grams += [self.pickerView selectedRowInComponent:2] * 10; |
grams += [self.pickerView selectedRowInComponent:1] * 100; |
grams += [self.pickerView selectedRowInComponent:0] * 1000; |
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NSDecimalNumber *ouncesDecimal; |
NSDecimalNumber *roundedOunces; |
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float ounces = grams / 28.349; |
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if (ounces >= 15.95) { |
NSInteger lbs = ounces / 16; |
ounces -= lbs * 16; |
if (ounces >= 15.95) { |
ounces = 0; |
lbs += 1; |
} |
ouncesDecimal = [[NSDecimalNumber alloc] initWithFloat:ounces]; |
roundedOunces = [ouncesDecimal decimalNumberByRoundingAccordingToBehavior:roundingBehavior]; |
self.label.text = [NSString stringWithFormat:@"%d lbs %@ oz", lbs, roundedOunces]; |
} |
else { |
ouncesDecimal = [[NSDecimalNumber alloc] initWithFloat:ounces]; |
roundedOunces = [ouncesDecimal decimalNumberByRoundingAccordingToBehavior:roundingBehavior]; |
self.label.text = [NSString stringWithFormat:@"%@ oz", roundedOunces]; |
} |
} |
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@end |
