UIButton setTitle:forState:问题

Question

为什么以下代码有效:

[signInBtn setTitleColor:[UIColor blackColor] forState:UIControlStateHighlighted];
[signInBtn setTitleColor:[UIColor blackColor] forState:UIControlStateDisabled];

虽然这不是:

[signInBtn setTitleColor:[UIColor blackColor] forState:UIControlStateHighlighted|UIControlStateDisabled];

Answer 1

我知道这是一个老问题,但这些答案都不正确.

当你单独设置每个state属性时,你说的属性应该是UIControlStateHighlightedOR UIControlStateDisabled而不是两者

当你按位或他们在一起时,你说他们必须同时设置在state属性中.含义 UIControlStateHighlightedAND UIControlStateDisabled在state属性中设置.

下面的示例代码完美地说明了我的观点.如果你不同意自己运行它.

[button setTitle:@"highlighted and selected" forState:UIControlStateHighlighted | UIControlStateSelected];
[button setTitle:@"Highlighted only" forState:UIControlStateHighlighted];
[button setTitle:@"Selected only" forState:UIControlStateSelected];
[button setTitle:@"Normal" forState:UIControlStateNormal];

NSLog(@"Normal title: %@", [[button titleLabel] text]); // prints title: Normal

[button setSelected:YES];

NSLog(@"Selected title: %@", [[button titleLabel] text]); // prints title: Selected only 

[button setSelected:NO];
[button setHighlighted:YES];

NSLog(@"highlighted title: %@", [[button titleLabel] text]); // prints title: Highlighted only

[button setSelected:YES];

NSLog(@"highlighted and selected title: %@", [[button titleLabel] text]); // prints title: highlighted and selected