Question

我创建了一个视图，并设置了两个属性backgroundColor和backgroundAlpha，当我设置v.background = color时，backgroundColor为蓝色，但是当我设置v.background = [color colorWithAlphaComponent:b]时， backgroundColor是清晰的，好像b是零;

+ (instancetype)initWithBgrColor:(UIColor *)color bgrAlpha:(NSInteger) b
{
    view *v = [[view alloc] init];
    v.backgroundColor = [color colorWithAlphaComponent:b];
    return v;
}

Answer 1

你一定不要看编译器的输出，看Xcode警告你参数类型。根据文档，colorWithAlphaComponent的alpha值参数是介于0.0和1.0之间的CGFloat，因此，您的NSInteger不正确。将您的代码更改为：

+ (instancetype)initWithBgrColor:(UIColor *)color bgrAlpha:(CGFloat) b
{
    NSLog(@"initWithBgrColor: b = %f", (float)b);
    view *v = [[view alloc] init];
    v.backgroundColor = [color colorWithAlphaComponent:b];
    return v;
}

https://developer.apple.com/reference/uikit/uicolor?language=objc

我的自定义视图不显示backgroundColor

1 个答案: